Chapter 5: Crime Scene Processing
Scene Security Supplies and Equipment
Adequate scene security supplies and equipment must be maintained.
That includes physical barriers, such as sawhorses and crime scene barrier tape, as well as rain protection devices, such as large plastic containers (in the event footprints or tire tracks must be protected from inclement weather) and waterproof tarpaulins.
Scene Documentation Supplies and Equipment
Scene documentation supplies and equipment must be immediately available to scene investigators, including clipboards, paper, pencils, measuring devices, flags, photographic equipment, and portable lighting.
Contingency plans should be formulated for the rapid replenishment of supplies and equipment should a scene examination require extraordinary resources.
Evidence Recovery Supplies and Equipment
Evidence recovery kits should contain containers such as test tubes, bottles, plastic and paper bags, boxes, rubber gloves, rubber bands, tweezers, print and impression recovery materials, and syringes.
A method must be in place to replenish stock once depleted. In one death case, 87 drinking glasses containing various levels of liquids and residue had to be examined.
All equipment and the vehicles used to transport the investigators and equipment to the scene must be properly maintained and ready to respond to a crime scene 24 hours a day.
Equipment and supplies must be adequately stocked on a continuous basis.
Written inventory control and replenishment procedures for equipment and supplies should be in place and a specific individual designated as responsible for maintenance and replenishment.
Although suitable field uniforms are commercially available for scene search work, any comfortable and durable clothing that may become soiled or damaged without concerning the wearer and that is suitable to the scene temperature may be adequate in all but the following specialized cases:
Scenes that contain biohazards, toxic materials, or vapors may require specialized protective clothing for scene investigators.
Large crime scenes or scenes where several investigating agencies may be working and investigators are not familiar with each other (such as a killing involving drug traffickers or a suspected serial killer) may require special identifying uniform clothing (or other controls such as badges or photo identification) in the interests of operational control.
Adequate battery- or generator-powered portable lighting should be available to investigators at all times in the event of outside scenes that must be searched during hours of darkness or indoor scenes that must be searched where electrical lighting is not available, either because of location or a power outage.
Responsibility for maintaining portable lighting and batteries should be contained in written operating procedures.
The appropriation of other specialized equipment and equipment operators should also be written into procedures.
Memorandums of understanding can be promulgated with fire departments and other specialized org-anizations for the provision of portable lighting and other special equipment when necessary, as such departments usually maintain lighting and other equipment as a matter of standard practice.
In investigating violent crimes, procedures must be in place for an organized and orderly response well in advance of notification of the occurrence of such a crime.
Procedures must be in writing and shared among all the agencies that potentially may become involved in an incident.
It is as important for each participant to understand what the function and role is of each member responding in an interagency sense as it is for each participant to understand the function and role within a particular agency (intra-agency responsibilities).
These advance understandings will do much to ensure a smooth and effective scene processing and should eliminate much of the on-scene confusion and squabbling too often encountered.
In violent crimes, several investigators should be mobilized if possible.
For example, sexual assault investigations require a minimum of three responding investigators.
Until all initial phases of the investigation have been completed, the suspect(s) and victim(s) should be kept separate from one another and never be transported in the same vehicles or occupy the same treatment, waiting, or interview rooms.
Contemporary agencies are implementing a conjoint team approach involving both law enforcement investigators and forensic nurse examiners, specifically in sexual assault, homicide, child abuse, elder abuse, and domestic violence cases.
In San Diego, California, police investigators request sexual assault nurse examiners (SANEs) at the scene and at the examination facility to assist in identifying crucial biomedical evidence often unrecognized by investigators without a medical background.
Increasingly, investigative agencies prefer that sexual assault examinations be performed by a credentialed SANE nurse following standards set by the International Association of Forensic Nurses (IAFN).
Transport to the crime scene should be done in a safe and lawful manner, with team organization (such as the fixing of responsibility for scene security, scene search, witness interviews, and area check) decided in advance.
This will ensure that the confusion that is typically present at scenes of violent crimes is not made worse by an arriving group of investigators who are not well organized.
Note Time, Date, and Weather Conditions
Investigators should note the time, date, and weather conditions at the scene upon arrival, as this can become important later when alibis of potential suspects are checked and when testifying in court.
Additionally, weather conditions may contribute to the cause or effect of the incident, which may not be realized until after the results have been discovered.
Make Initial Observations of the Scene
Several assessments of a scene must be made simultaneously by arriving investigators to evaluate relative danger, scene scope, control of individuals at the scene, and the coordination of responsibilities.
Nature of Scene (Immediate Danger)
A rapid assessment of the condition of the scene should be made in order to rule out potential danger to the investigator(s) or others.
Such dangers may include the presence of dangerous person(s), weather problems, toxic or otherwise dangerous gases or substances, seismic activity, electrical hazards, fire danger, potentially dangerous plants or animals, and possible avalanche, mudslide, or rock slide, or dangerous structures.
Suspects, Victims, and Witnesses
The identification of suspect(s), victim(s), and witnesses at the scene, if any, should immediately be made and decisions reached as to the treatment of each.
As a minimum, suspect(s) and victim(s) should be separated and, when possible, witnesses should be separated from each other and interviewed separately so that one does not color another's perception of an incident.
As soon as a suspect meets the legal requirements for apprehension, that individual should be placed in police custody.
Even though an individual at the scene does not appear, at the moment, to be a suspect, victim, or witness, complete identification (including address and telephone number) is still needed in the event there is a need to recontact that person in the future.
Police
Police officials present at a crime scene must be identified and the senior official present of the agency with primary jurisdiction must take charge of the scene.
In some cases, specialized agencies may share jurisdiction, so both senior officials must work in an organized and coordinated way to ensure optimal identification, collection, and preservation of evidence.
The senior official must inspect the credentials of other officially authorized persons seeking admission to the investigation or the scene, especially if the senior official does not personally know the individuals.
Other Agencies
All police officials present at the scene should be identified and the senior official present of the agency with primary jurisdiction must take charge of the scene.
In certain cases, specialized agencies may also share jurisdiction.
The senior official must inspect the credentials of other officially authorized persons seeking admission to the investigation or the scene.
Agencies without official authorization but with an interest in the scene must be controlled and not permitted access to the scene.
Personnel from unauthorized agencies may use subterfuge or intimidation to gain access to the scene.
Assure Medical Aid
Paramedics must provide immediate medical aid to seriously injured or ill persons at the scene, regardless of the need to locate, recover, and preserve evidence.
Minor illnesses or injuries may be treated at the expense of identification and recovery of evidence.
Paramedical personnel should be trained in the ability to render emergency treatment swiftly while preserving evidence, such as rapid removal of clothing without altering defects or contaminating it.
Responding healthcare personnel and investigators should coordinate with the individual possessing the most knowledge about the scene and the incident to prevent interference in the securing and investigation of the crime scene and to establish the physical parameters of the scene.
For example, normally in a situation where a sexual assault occurred within a single-family residence, the secured area of the scene would include the house and the adjoining property.
However, if a witness saw an individual run from the house in a certain direction, leap a fence, and run through three adjoining vacant lots before getting into a car parked on the next block, the size of the scene to be secured may be greatly expanded.
One important consideration cited by police for the conjoint team approach with forensic nurses concerns the ability of the nurse to elicit often sensitive information from victims and grieving families who may be in shock or may be intimidated by a uniformed officer.
This technique may be commonly lacking with officers who may not be skilled in psychosocial intervention.
Environment security
Nonhuman environmental elements, such as weather, animals, and unnatural elements, may damage or obliterate a crime scene.
These should be stabilized to the maximum extent possible, not only to preserve evidence but also to provide for the safety of those examining the scene.
Weather security
The scene should be protected from weather elements when necessary.
Fragile evidence, such as tire tracks and footprints, should be covered and guarded until the weather clears and recovery efforts can begin.
Animal security
A crime scene may be destroyed, damaged, or significantly altered by any number of animals in a variety of settings.
Scene security procedures should include protection of the scene from not only birds, insects, and other wild animals but domestic animals as well.
Although some animals may not be particularly dangerous to evidence at the scene itself, they may be quite dangerous to investigators searching the scene.
Accordingly, investigators should use extreme caution when working in the unknown habitats of animals such as poisonous snakes, spiders, scorpions, and exotic animals kept as pets.
Security in emergencies
In some situations, emergency response personnel, such as firefighters, hazardous materials specialists, and engineers, must make rapid decisions to protect life and property from further danger and destruction.
Often this action requires the employment of water, chemicals, explosives, or other interventions.
Although evidence discovery and preservation may have to occupy a secondary place in the face of emergency action, continuous coordination and cooperation should be maintained with emergency response personnel to minimize evidence destruction
Security concerning suspects
A quick check should be made to determine the presence of any suspects or others who are potentially a danger to the scene or the individuals processing it.
Places in which a human could escape detection should be checked, as it can be disconcerting to come face to face with an armed suspect upon opening the door of a closet.
Persons found at the scene should be placed in custody.
Security concerning witnesses and victims
Witnesses, victims, and others (“bystanders”) should be identified and removed from the scene.
Victims should be interviewed to determine what parts of the crime scene should receive particular attention.
Victims should be transported to the appropriate healthcare facility for examination and continued investigation.
Victims should not be allowed to bathe or change clothes until examined.
It is difficult to ensure that certain scenes are cleared of victims and witnesses, especially if they are located at the home of a victim or witness.
There are skillful and diplomatic ways in which such situations may be approached, but prior training in these techniques is required.
Security concerning officials
Often, high-ranking officials may wish to visit the scene for a variety of purposes. Ideally, anyone not directly involved in the search of the scene for evidence should be excluded.
However, reality dictates that investigators searching a crime scene are occasionally interrupted by officials demanding to inspect the scene.
When this occurs, investigators should suspend their search, accompany the inspecting officials, and ensure that officials do not disturb or alter the scene in any way.
Security concerning investigators
Investigators must move through crime scenes with utmost caution and avoid bringing items into the scene for convenience.
The scene should be kept "clean" and individual items of equipment and supplies should be brought in only as needed. Investigators must never use any telephone, appliance, or other convenience at the scene unless necessary to process the scene.
Even the necessity of turning on or off lights or gas or a motor should be done to ensure evidence is not disturbed.
Security concerning admission
Once the scene is secured, it must stay secured.
Only one entrance/exit to the scene must be permitted, and that point must be guarded and controlled by a competent official, preferably an experienced police officer.
It must be made clear exactly who is to be permitted into the scene and that all others are to be excluded unless the senior official in charge of the scene grants an exception.
A detailed log must be maintained of the times, dates, and complete identities of all persons entering and exiting the scene. This log becomes a permanent part of the investigative case file.
When the treatment room is a crime scene
Death or serious injury may occur in the clinical environs: the trauma room, operating room, emergency department, delivery room, and so forth.
Consideration must be given to protecting and securing these areas in the same manner as other violent crime scenes.
Particular attention should be paid to access, inventory of supplies and medications, and records, including computerized records.
It is especially important in these cases that an individual on the investigative team possess medicolegal forensic skills and education in order to minimize conflicts of interest between the institution and the investigation
Conduct Preliminary Interviews
As previously stated, preliminary interviews of persons with knowledge of the scene and incident should be conducted. Armed with such information, investigators can begin searching the scene with some frames of reference that will permit specific attention to various areas of the scene.
Take Overall Scene Photographs
Overall photographs of the scene should be taken before beginning the search to preserve an image of the scene before the evidence search and recovery process disturbs it.
These photographs also help to resolve any future questions concerning the original condition of the scene or if scene reconstruction becomes necessary.
It may be appropriate to have aerial photographs taken of the scene, especially if the scene is outdoors and contains many items of physical evidence.
Determine the Method of Search
Line or strip search: Works best on large, outdoor scenes; requires a search coordinator; uses volunteers who require preliminary instructions
Grid method: Modified double line search as above; effective but time consuming
Spiral method: Inward or outward spirals; best used on crime scenes with no physical barriers (e.g., open water); requires the ability to trace a regular pattern with fixed diameters; limited application
Zone method: Best used on scenes with defined zones or areas; effective in houses or buildings; teams are assigned small zones for searching; combined with other methods; good for warrant searches
Link method: Based on linkage theory; most common and productive; one type of evidence leads to another; experimental, logical, and systematic; works with large and small, indoor and outdoor scenes.
Wheel or ray method: Used for specialsituations; limited applications; best used on small, circular crime scenes
Searching
The crime scene should be thoroughly searched, using one of the first five scene search patterns.
Particular attention must be paid to the possible existence of trace evidence, such as hairs, fibers, and stains, in very small quantities.
This attention to detail requires the use of enhanced lighting, alternative light sources, and magnification devices.
Sketching
The main purpose of a crime scene search is to locate and document the location of evidence, rather than to recover it.
If fragile evidence is located and must be photographed, measured, recovered, and preserved immediately, it should be done at the time of discovery.
Intruders should be dealt with and escorted in such a way that they are not permitted to contaminate the scene.
As evidence is identified, some mechanism must be in place to mark the location so that the evidence can be recovered.
Such a mechanism must also serve as a warning to others working in the scene that this specific location contains evidence.
This marking is especially valuable in outdoor scenes where plant growth or other obstacles may obscure the location of the evidentiary material.
Small colored flags attached to stiff wires are often useful in achieving this task in outdoor scenes.
In addition to searching the scene in natural light, using battery-powered, portable artificial lighting in daylight may help to reveal evidence because small objects may reflect light at certain angles.
The use of battery-powered artificial light at crime scenes with insufficient natural light (such as at night or in places with inadequate lighting) may be necessary as well, and therefore, such equipment must be available for immediate use.
Often, especially in sexual assault cases, portable ultraviolet lighting is useful in detecting articles and stains that may fluoresce under ultraviolet light while remaining invisible in other light sources.
The Omnichrome 1000, used on deceased bodies, is now used on living victims of sexual assault.
Infrared videography may assist the investigator in the detection of bruises not visible in conventional lighting and is especially useful in the investigation of crimes involving child abuse and battered victims.
Fix Locations of Evidence and Measure to Fixed Objects
Measurements must be taken from three fixed objects to three definable points on each piece of evidence to determine the exact location of the scene.
These measurements should be indicated on the scene sketch and recorded in a logbook.
Rephotograph the Entire Scene with Evidence Spotted
Photographs of the entire scene should show where evidence has been spotted to provide an impression of the relationship of each piece of evidence to the other.
Outdoor scenes and especially large scenes with many items of evidence may benefit greatly from aerial photography.
Nature of Identifying Mark
Generally it is sufficient to mark evidence with the time and date of recovery, along with the initials of the investigator recovering the evidence.
The marks should be applied so that they are difficult to remove, but they must not obscure any potential evidentiary features.
Location of Identifying Marks
Identifying marks should be placed on an object as far away from the surfaces of the objects that are going to be examined.
In some cases, only the container in which the evidence is placed should be marked.
If in doubt, it is best to avoid marking the individual piece of evidence and just mark the container into which the evidence is placed.
This method should not be problematic if the integrity of the chain of custody is maintained.
Evidence Preservation and Integrity as the Primary Concern
The key focus in evidence recovery is to ensure preservation of the evidence in order to maximize the capabilities of the forensic laboratory.
This requires close attention to the recovery and preservation protocols, as well as close coordination with laboratory personnel to ascertain the latest preferred methods of recovering and preserving evidence.
It is important to ensure that the chain of custody is not broken and that the evidence is adequately identifiable from the time of recovery until the disposition of the case.
It is safest to recover the evidence in an uncontaminated state when possible, marking the container in which the evidence is placed with the time, date, and initials of the recovering investigator.
Improper marking may taint or obliterate important evidentiary materials.
Recovery of Possible Print Evidence
Evidence that may possibly have fingerprint or other print evidence should be marked as such.
Precautions must be taken to prevent abrasions on the surface of an item that may obliterate or obscure print evidence.
Recovery of Trace Evidence
Trace evidence should be recovered as intact as possible. In recovering stains, hairs, or fibers, for example, the material on which the item is found should be recovered along with the item, if practical.
For example, in the recovery of a hair adhering to a stain on a garment or a large cardboard box, it would be advisable to recover the entire garment or a portion of the cardboard box.
Recovery of Perishable Biological Evidence
Perishable biological evidence should be recovered quickly and air-dried without heat in a dust-free atmosphere.
Plastic packaging should be avoided due to condensation, and commercial evidence packaging materials firms should be contacted for advice on new packaging advances.
In many medical facilities, contaminated materials should be placed in biohazard plastic bags, but the paper bag should be sealed and marked before being placed in the plastic bag.
Evidence removal
All evidence identified and recovered at the scene should be inventoried, logged, and removed, maintaining the preservation and security of the evidence.
The inventory and log becomes a permanent part of the case file.
Equipment removal
The scene should be resurveyed to ensure that all materials brought into or near the scene have been recovered, such as crime scene search equipment, cameras, and other materials.
Although this step sounds simplistic, since this practice was initiated in the 1980s, some rather incredible lapses of judgment have been observed, such as investigators leaving behind cameras, their badges and credentials, their own clothing, and even individual items of evidence.
Arrangement for continuing security
A crime scene must be secured to prevent significant property loss or vandalism. In some cases, the scene is sealed for reinvestigation, while in others, it is relinquished to the legal occupier of the property.
In these cases, assistance and advice should be provided to help the property owner resecure the property.
Scene departure
The final step, scene departure, marks a formal exit from the scene by investigators, with the intent not to return.
If, for any reason, there is doubt as to the finality of this move, the scene should not be released and should stay the subject of continued security until such time as it is considered suitable for release.
Scene Security Supplies and Equipment
Adequate scene security supplies and equipment must be maintained.
That includes physical barriers, such as sawhorses and crime scene barrier tape, as well as rain protection devices, such as large plastic containers (in the event footprints or tire tracks must be protected from inclement weather) and waterproof tarpaulins.
Scene Documentation Supplies and Equipment
Scene documentation supplies and equipment must be immediately available to scene investigators, including clipboards, paper, pencils, measuring devices, flags, photographic equipment, and portable lighting.
Contingency plans should be formulated for the rapid replenishment of supplies and equipment should a scene examination require extraordinary resources.
Evidence Recovery Supplies and Equipment
Evidence recovery kits should contain containers such as test tubes, bottles, plastic and paper bags, boxes, rubber gloves, rubber bands, tweezers, print and impression recovery materials, and syringes.
A method must be in place to replenish stock once depleted. In one death case, 87 drinking glasses containing various levels of liquids and residue had to be examined.
All equipment and the vehicles used to transport the investigators and equipment to the scene must be properly maintained and ready to respond to a crime scene 24 hours a day.
Equipment and supplies must be adequately stocked on a continuous basis.
Written inventory control and replenishment procedures for equipment and supplies should be in place and a specific individual designated as responsible for maintenance and replenishment.
Although suitable field uniforms are commercially available for scene search work, any comfortable and durable clothing that may become soiled or damaged without concerning the wearer and that is suitable to the scene temperature may be adequate in all but the following specialized cases:
Scenes that contain biohazards, toxic materials, or vapors may require specialized protective clothing for scene investigators.
Large crime scenes or scenes where several investigating agencies may be working and investigators are not familiar with each other (such as a killing involving drug traffickers or a suspected serial killer) may require special identifying uniform clothing (or other controls such as badges or photo identification) in the interests of operational control.
Adequate battery- or generator-powered portable lighting should be available to investigators at all times in the event of outside scenes that must be searched during hours of darkness or indoor scenes that must be searched where electrical lighting is not available, either because of location or a power outage.
Responsibility for maintaining portable lighting and batteries should be contained in written operating procedures.
The appropriation of other specialized equipment and equipment operators should also be written into procedures.
Memorandums of understanding can be promulgated with fire departments and other specialized org-anizations for the provision of portable lighting and other special equipment when necessary, as such departments usually maintain lighting and other equipment as a matter of standard practice.
In investigating violent crimes, procedures must be in place for an organized and orderly response well in advance of notification of the occurrence of such a crime.
Procedures must be in writing and shared among all the agencies that potentially may become involved in an incident.
It is as important for each participant to understand what the function and role is of each member responding in an interagency sense as it is for each participant to understand the function and role within a particular agency (intra-agency responsibilities).
These advance understandings will do much to ensure a smooth and effective scene processing and should eliminate much of the on-scene confusion and squabbling too often encountered.
In violent crimes, several investigators should be mobilized if possible.
For example, sexual assault investigations require a minimum of three responding investigators.
Until all initial phases of the investigation have been completed, the suspect(s) and victim(s) should be kept separate from one another and never be transported in the same vehicles or occupy the same treatment, waiting, or interview rooms.
Contemporary agencies are implementing a conjoint team approach involving both law enforcement investigators and forensic nurse examiners, specifically in sexual assault, homicide, child abuse, elder abuse, and domestic violence cases.
In San Diego, California, police investigators request sexual assault nurse examiners (SANEs) at the scene and at the examination facility to assist in identifying crucial biomedical evidence often unrecognized by investigators without a medical background.
Increasingly, investigative agencies prefer that sexual assault examinations be performed by a credentialed SANE nurse following standards set by the International Association of Forensic Nurses (IAFN).
Transport to the crime scene should be done in a safe and lawful manner, with team organization (such as the fixing of responsibility for scene security, scene search, witness interviews, and area check) decided in advance.
This will ensure that the confusion that is typically present at scenes of violent crimes is not made worse by an arriving group of investigators who are not well organized.
Note Time, Date, and Weather Conditions
Investigators should note the time, date, and weather conditions at the scene upon arrival, as this can become important later when alibis of potential suspects are checked and when testifying in court.
Additionally, weather conditions may contribute to the cause or effect of the incident, which may not be realized until after the results have been discovered.
Make Initial Observations of the Scene
Several assessments of a scene must be made simultaneously by arriving investigators to evaluate relative danger, scene scope, control of individuals at the scene, and the coordination of responsibilities.
Nature of Scene (Immediate Danger)
A rapid assessment of the condition of the scene should be made in order to rule out potential danger to the investigator(s) or others.
Such dangers may include the presence of dangerous person(s), weather problems, toxic or otherwise dangerous gases or substances, seismic activity, electrical hazards, fire danger, potentially dangerous plants or animals, and possible avalanche, mudslide, or rock slide, or dangerous structures.
Suspects, Victims, and Witnesses
The identification of suspect(s), victim(s), and witnesses at the scene, if any, should immediately be made and decisions reached as to the treatment of each.
As a minimum, suspect(s) and victim(s) should be separated and, when possible, witnesses should be separated from each other and interviewed separately so that one does not color another's perception of an incident.
As soon as a suspect meets the legal requirements for apprehension, that individual should be placed in police custody.
Even though an individual at the scene does not appear, at the moment, to be a suspect, victim, or witness, complete identification (including address and telephone number) is still needed in the event there is a need to recontact that person in the future.
Police
Police officials present at a crime scene must be identified and the senior official present of the agency with primary jurisdiction must take charge of the scene.
In some cases, specialized agencies may share jurisdiction, so both senior officials must work in an organized and coordinated way to ensure optimal identification, collection, and preservation of evidence.
The senior official must inspect the credentials of other officially authorized persons seeking admission to the investigation or the scene, especially if the senior official does not personally know the individuals.
Other Agencies
All police officials present at the scene should be identified and the senior official present of the agency with primary jurisdiction must take charge of the scene.
In certain cases, specialized agencies may also share jurisdiction.
The senior official must inspect the credentials of other officially authorized persons seeking admission to the investigation or the scene.
Agencies without official authorization but with an interest in the scene must be controlled and not permitted access to the scene.
Personnel from unauthorized agencies may use subterfuge or intimidation to gain access to the scene.
Assure Medical Aid
Paramedics must provide immediate medical aid to seriously injured or ill persons at the scene, regardless of the need to locate, recover, and preserve evidence.
Minor illnesses or injuries may be treated at the expense of identification and recovery of evidence.
Paramedical personnel should be trained in the ability to render emergency treatment swiftly while preserving evidence, such as rapid removal of clothing without altering defects or contaminating it.
Responding healthcare personnel and investigators should coordinate with the individual possessing the most knowledge about the scene and the incident to prevent interference in the securing and investigation of the crime scene and to establish the physical parameters of the scene.
For example, normally in a situation where a sexual assault occurred within a single-family residence, the secured area of the scene would include the house and the adjoining property.
However, if a witness saw an individual run from the house in a certain direction, leap a fence, and run through three adjoining vacant lots before getting into a car parked on the next block, the size of the scene to be secured may be greatly expanded.
One important consideration cited by police for the conjoint team approach with forensic nurses concerns the ability of the nurse to elicit often sensitive information from victims and grieving families who may be in shock or may be intimidated by a uniformed officer.
This technique may be commonly lacking with officers who may not be skilled in psychosocial intervention.
Environment security
Nonhuman environmental elements, such as weather, animals, and unnatural elements, may damage or obliterate a crime scene.
These should be stabilized to the maximum extent possible, not only to preserve evidence but also to provide for the safety of those examining the scene.
Weather security
The scene should be protected from weather elements when necessary.
Fragile evidence, such as tire tracks and footprints, should be covered and guarded until the weather clears and recovery efforts can begin.
Animal security
A crime scene may be destroyed, damaged, or significantly altered by any number of animals in a variety of settings.
Scene security procedures should include protection of the scene from not only birds, insects, and other wild animals but domestic animals as well.
Although some animals may not be particularly dangerous to evidence at the scene itself, they may be quite dangerous to investigators searching the scene.
Accordingly, investigators should use extreme caution when working in the unknown habitats of animals such as poisonous snakes, spiders, scorpions, and exotic animals kept as pets.
Security in emergencies
In some situations, emergency response personnel, such as firefighters, hazardous materials specialists, and engineers, must make rapid decisions to protect life and property from further danger and destruction.
Often this action requires the employment of water, chemicals, explosives, or other interventions.
Although evidence discovery and preservation may have to occupy a secondary place in the face of emergency action, continuous coordination and cooperation should be maintained with emergency response personnel to minimize evidence destruction
Security concerning suspects
A quick check should be made to determine the presence of any suspects or others who are potentially a danger to the scene or the individuals processing it.
Places in which a human could escape detection should be checked, as it can be disconcerting to come face to face with an armed suspect upon opening the door of a closet.
Persons found at the scene should be placed in custody.
Security concerning witnesses and victims
Witnesses, victims, and others (“bystanders”) should be identified and removed from the scene.
Victims should be interviewed to determine what parts of the crime scene should receive particular attention.
Victims should be transported to the appropriate healthcare facility for examination and continued investigation.
Victims should not be allowed to bathe or change clothes until examined.
It is difficult to ensure that certain scenes are cleared of victims and witnesses, especially if they are located at the home of a victim or witness.
There are skillful and diplomatic ways in which such situations may be approached, but prior training in these techniques is required.
Security concerning officials
Often, high-ranking officials may wish to visit the scene for a variety of purposes. Ideally, anyone not directly involved in the search of the scene for evidence should be excluded.
However, reality dictates that investigators searching a crime scene are occasionally interrupted by officials demanding to inspect the scene.
When this occurs, investigators should suspend their search, accompany the inspecting officials, and ensure that officials do not disturb or alter the scene in any way.
Security concerning investigators
Investigators must move through crime scenes with utmost caution and avoid bringing items into the scene for convenience.
The scene should be kept "clean" and individual items of equipment and supplies should be brought in only as needed. Investigators must never use any telephone, appliance, or other convenience at the scene unless necessary to process the scene.
Even the necessity of turning on or off lights or gas or a motor should be done to ensure evidence is not disturbed.
Security concerning admission
Once the scene is secured, it must stay secured.
Only one entrance/exit to the scene must be permitted, and that point must be guarded and controlled by a competent official, preferably an experienced police officer.
It must be made clear exactly who is to be permitted into the scene and that all others are to be excluded unless the senior official in charge of the scene grants an exception.
A detailed log must be maintained of the times, dates, and complete identities of all persons entering and exiting the scene. This log becomes a permanent part of the investigative case file.
When the treatment room is a crime scene
Death or serious injury may occur in the clinical environs: the trauma room, operating room, emergency department, delivery room, and so forth.
Consideration must be given to protecting and securing these areas in the same manner as other violent crime scenes.
Particular attention should be paid to access, inventory of supplies and medications, and records, including computerized records.
It is especially important in these cases that an individual on the investigative team possess medicolegal forensic skills and education in order to minimize conflicts of interest between the institution and the investigation
Conduct Preliminary Interviews
As previously stated, preliminary interviews of persons with knowledge of the scene and incident should be conducted. Armed with such information, investigators can begin searching the scene with some frames of reference that will permit specific attention to various areas of the scene.
Take Overall Scene Photographs
Overall photographs of the scene should be taken before beginning the search to preserve an image of the scene before the evidence search and recovery process disturbs it.
These photographs also help to resolve any future questions concerning the original condition of the scene or if scene reconstruction becomes necessary.
It may be appropriate to have aerial photographs taken of the scene, especially if the scene is outdoors and contains many items of physical evidence.
Determine the Method of Search
Line or strip search: Works best on large, outdoor scenes; requires a search coordinator; uses volunteers who require preliminary instructions
Grid method: Modified double line search as above; effective but time consuming
Spiral method: Inward or outward spirals; best used on crime scenes with no physical barriers (e.g., open water); requires the ability to trace a regular pattern with fixed diameters; limited application
Zone method: Best used on scenes with defined zones or areas; effective in houses or buildings; teams are assigned small zones for searching; combined with other methods; good for warrant searches
Link method: Based on linkage theory; most common and productive; one type of evidence leads to another; experimental, logical, and systematic; works with large and small, indoor and outdoor scenes.
Wheel or ray method: Used for specialsituations; limited applications; best used on small, circular crime scenes
Searching
The crime scene should be thoroughly searched, using one of the first five scene search patterns.
Particular attention must be paid to the possible existence of trace evidence, such as hairs, fibers, and stains, in very small quantities.
This attention to detail requires the use of enhanced lighting, alternative light sources, and magnification devices.
Sketching
The main purpose of a crime scene search is to locate and document the location of evidence, rather than to recover it.
If fragile evidence is located and must be photographed, measured, recovered, and preserved immediately, it should be done at the time of discovery.
Intruders should be dealt with and escorted in such a way that they are not permitted to contaminate the scene.
As evidence is identified, some mechanism must be in place to mark the location so that the evidence can be recovered.
Such a mechanism must also serve as a warning to others working in the scene that this specific location contains evidence.
This marking is especially valuable in outdoor scenes where plant growth or other obstacles may obscure the location of the evidentiary material.
Small colored flags attached to stiff wires are often useful in achieving this task in outdoor scenes.
In addition to searching the scene in natural light, using battery-powered, portable artificial lighting in daylight may help to reveal evidence because small objects may reflect light at certain angles.
The use of battery-powered artificial light at crime scenes with insufficient natural light (such as at night or in places with inadequate lighting) may be necessary as well, and therefore, such equipment must be available for immediate use.
Often, especially in sexual assault cases, portable ultraviolet lighting is useful in detecting articles and stains that may fluoresce under ultraviolet light while remaining invisible in other light sources.
The Omnichrome 1000, used on deceased bodies, is now used on living victims of sexual assault.
Infrared videography may assist the investigator in the detection of bruises not visible in conventional lighting and is especially useful in the investigation of crimes involving child abuse and battered victims.
Fix Locations of Evidence and Measure to Fixed Objects
Measurements must be taken from three fixed objects to three definable points on each piece of evidence to determine the exact location of the scene.
These measurements should be indicated on the scene sketch and recorded in a logbook.
Rephotograph the Entire Scene with Evidence Spotted
Photographs of the entire scene should show where evidence has been spotted to provide an impression of the relationship of each piece of evidence to the other.
Outdoor scenes and especially large scenes with many items of evidence may benefit greatly from aerial photography.
Nature of Identifying Mark
Generally it is sufficient to mark evidence with the time and date of recovery, along with the initials of the investigator recovering the evidence.
The marks should be applied so that they are difficult to remove, but they must not obscure any potential evidentiary features.
Location of Identifying Marks
Identifying marks should be placed on an object as far away from the surfaces of the objects that are going to be examined.
In some cases, only the container in which the evidence is placed should be marked.
If in doubt, it is best to avoid marking the individual piece of evidence and just mark the container into which the evidence is placed.
This method should not be problematic if the integrity of the chain of custody is maintained.
Evidence Preservation and Integrity as the Primary Concern
The key focus in evidence recovery is to ensure preservation of the evidence in order to maximize the capabilities of the forensic laboratory.
This requires close attention to the recovery and preservation protocols, as well as close coordination with laboratory personnel to ascertain the latest preferred methods of recovering and preserving evidence.
It is important to ensure that the chain of custody is not broken and that the evidence is adequately identifiable from the time of recovery until the disposition of the case.
It is safest to recover the evidence in an uncontaminated state when possible, marking the container in which the evidence is placed with the time, date, and initials of the recovering investigator.
Improper marking may taint or obliterate important evidentiary materials.
Recovery of Possible Print Evidence
Evidence that may possibly have fingerprint or other print evidence should be marked as such.
Precautions must be taken to prevent abrasions on the surface of an item that may obliterate or obscure print evidence.
Recovery of Trace Evidence
Trace evidence should be recovered as intact as possible. In recovering stains, hairs, or fibers, for example, the material on which the item is found should be recovered along with the item, if practical.
For example, in the recovery of a hair adhering to a stain on a garment or a large cardboard box, it would be advisable to recover the entire garment or a portion of the cardboard box.
Recovery of Perishable Biological Evidence
Perishable biological evidence should be recovered quickly and air-dried without heat in a dust-free atmosphere.
Plastic packaging should be avoided due to condensation, and commercial evidence packaging materials firms should be contacted for advice on new packaging advances.
In many medical facilities, contaminated materials should be placed in biohazard plastic bags, but the paper bag should be sealed and marked before being placed in the plastic bag.
Evidence removal
All evidence identified and recovered at the scene should be inventoried, logged, and removed, maintaining the preservation and security of the evidence.
The inventory and log becomes a permanent part of the case file.
Equipment removal
The scene should be resurveyed to ensure that all materials brought into or near the scene have been recovered, such as crime scene search equipment, cameras, and other materials.
Although this step sounds simplistic, since this practice was initiated in the 1980s, some rather incredible lapses of judgment have been observed, such as investigators leaving behind cameras, their badges and credentials, their own clothing, and even individual items of evidence.
Arrangement for continuing security
A crime scene must be secured to prevent significant property loss or vandalism. In some cases, the scene is sealed for reinvestigation, while in others, it is relinquished to the legal occupier of the property.
In these cases, assistance and advice should be provided to help the property owner resecure the property.
Scene departure
The final step, scene departure, marks a formal exit from the scene by investigators, with the intent not to return.
If, for any reason, there is doubt as to the finality of this move, the scene should not be released and should stay the subject of continued security until such time as it is considered suitable for release.
