Chapter 2-Crime Scene Investigation

What is the primary goal of a crime-scene investigation?

To recognize, document, photograph, and collect evidence at the scene of a crime.

What types of evidence can link a suspect to a crime scene?

Hair, fibers, pollen, fingerprints, or human cells.

Why is it crucial for crime-scene investigators to secure the crime scene?

To prevent loss or contamination of evidence.

What are the stringent guidelines for evidence acceptability?

Evidence must be sufficient, scientific, reliable, and valid.

What is the role of Scientific Working Groups (SWGs) in forensic science?

To revise and standardize protocols for evidence collection and testing.

Who typically arrives first at a crime scene?

Police officers.

What is the responsibility of crime-scene investigators (CSIs)?

To document the crime scene in detail and collect physical evidence.

What do medical examiners determine at a crime scene?

The manner of death: natural, accidental, homicide, suicide, or undetermined.

What is trace evidence?

Materials transferred from one person or object to another during contact.

What principle did Dr. Edmond Locard establish regarding evidence transfer?

Locard's Principle of Exchange states that physical evidence can be cross-transferred when entities come into contact.

What are two types of evidence classified in forensic investigations?

Direct evidence and circumstantial evidence.

What constitutes direct evidence?

Firsthand observations such as eyewitness accounts or confessions.

How is circumstantial evidence defined?

Indirect evidence that implies a fact but does not prove it.

What can forensic anthropologists determine from human bones?

Factors such as sex, age, height, weight, and ethnic background of the victim.

What might a botanist determine from plant material at a crime scene?

The time of year or region of the world in which a crime took place.

How can an entomologist assist in a crime investigation?

By estimating the time since death through the study of insects colonizing a body.

What is the significance of the National Academy of Science Report in 2009?

It called for more scientific approaches to evidence and evidence testing.

What is the role of detectives in a crime-scene investigation?

To interview witnesses and specialists to gather evidence for reconstructing the crime scene.

What is an example of trace evidence found at a crime scene?

Pet hair on clothes or fingerprints on a glass.

What does the intensity, duration, and nature of contact affect in evidence transfer?

The extent of the transfer of physical evidence.

What is a common misconception about finding fingerprints or hair at a crime scene?

They do not provide clues as to when the exchange occurred.

What is the importance of evidence being collected using accepted protocols?

To ensure it is valid and can be accepted in court.

What might happen if evidence is not properly collected?

It may be deemed inadmissible in court.

What is circumstantial evidence?

Evidence that provides a link between a crime scene and a suspect, such as finding a suspect's gun at a shooting site.

What are the two types of circumstantial evidence?

Physical evidence and biological evidence.

What does physical evidence include?

Impressions like fingerprints, footprints, shoe prints, tire impressions, tool marks, glass, soil, fibers, weapons, bullets, and shell casings.

What does biological evidence include?

DNA in tissue, bodily fluids, hair, plants, pollen, and natural fibers.

How does biological evidence affect the group of suspects?

It can reduce the group to a single individual, making it more persuasive in court.

What is class evidence?

Evidence that narrows identity to a group of persons or things, such as ABO blood type.

What is individual evidence?

Evidence that narrows identity to a single person or thing, typically unique like a fingerprint or DNA.

What are the seven S's of crime scene investigation?

Securing the scene, separating witnesses, scanning the scene, seeing the scene, sketching the scene, searching for evidence, and securing and collecting evidence.

What is the first step in securing a crime scene?

The first responding officer prioritizes safety and preserves evidence by restricting unauthorized access.

Why is it important to separate witnesses at a crime scene?

To prevent collusion and ensure accurate, independent accounts of the events.

What is the purpose of scanning the scene?

To determine where photos should be taken and to identify primary and secondary crime scenes.

What is triangulation in crime scene investigation?

A technique used to record evidence location from two fixed reference points.

What should a crime scene sketch include?

The position of remains, evidence, measurements from immovable landmarks, and a labeled north direction.

What factors influence the type of search pattern used in evidence searching?

The size of the area and the number of investigators.

What are some examples of search patterns used in crime scene investigations?

Gridded, linear, spiral, zone, and quadrant patterns.

How should biological evidence be stored?

In breathable containers to allow drying and reduce mold contamination.

What is a paper bindle used for?

To contain trace evidence after it has dried.

What technology can assist in locating remains and evidence?

Thermal imaging, satellite imaging, and ground-penetrating radar.

What is Locard's Principle of Exchange?

The principle that transfer, loss, or contamination of evidence can occur if the crime scene is left unsecured.

What is the role of the first responding officer at a crime scene?

To secure the scene, preserve evidence, and maintain a security log of visitors.

What questions should be asked of each witness?

When did the crime occur? Who notified law enforcement? Who is the victim? Can the perpetrator be identified? What did you see happen? Where were you when you observed the crime scene?

What is a paper bindle used for in evidence collection?

A paper bindle is used to contain trace evidence after it has air dried.

What should be done to the outer container of evidence?

The outer container should be sealed with tape and labeled with the collector's signature across the tape.

How is the size of the paper bindle determined?

The size of the paper bindle depends on the size of the evidence.

What are the steps to prepare a paper bindle for evidence collection?

1. Choose the appropriate size sheet of clean paper. 2. Crease the paper. 3. Place evidence in the designated location. 4. Fold the sides in. 5. Fold the top and bottom. 6. Tape the bindle closed. 7. Place it inside a plastic or paper evidence bag. 8. Seal the bag and have the collector write their name over the folded edge.

What must be done before handling each piece of evidence?

Crime-scene evidence collectors should change gloves.

What information should be included in an evidence log?

The evidence log should include case number, item inventory number, description of the evidence, name of suspect, name of victim, date and time of recovery, and signatures of the person recovering the evidence and any witnesses.

What is the purpose of control samples in evidence collection?

Control samples, such as hair and fibers, are obtained for exclusion purposes to compare with evidence found at the crime scene.

What is the chain of custody?

The chain of custody is a record of the transfer of evidence, ensuring it is tracked from the crime scene to the courtroom.

What should be done with the evidence container after sealing it?

The container should be labeled with pertinent information and given to the next person for transport to the lab.

How should evidence be documented at a crime scene?

All evidence should be accurately documented regarding its precise location.

What is a datum point in evidence collection?

A datum point is a permanent, fixed point of reference used to establish the collection site.

What is the purpose of establishing a north corner in a collection site?

The north corner serves as a reference point for measuring and marking evidence positions.

How is the location of evidence measured?

The location is measured by the perpendicular distances from the evidence to the reference lines along the perimeter of the collection site.

What is the role of forensic laboratories in evidence processing?

Forensic laboratories process all evidence collected at the crime scene and provide results to the lead detective.

What is the importance of evidence analysis in criminal investigations?

Evidence analysis can link a suspect to a scene or victim, establish identities, confirm witness testimony, or acquit the innocent.

What is crime-scene reconstruction?

Crime-scene reconstruction involves forming a hypothesis of the sequence of events from before the crime was committed through its commission.

Why is it important for investigators to maintain an open mind?

To examine all possibilities and avoid biases in interpreting evidence.

What is the difference between direct evidence and circumstantial evidence?

Direct evidence directly supports a fact, while circumstantial evidence does not.

What must be shared with the defense during legal proceedings?

All information in the possession of the prosecution.

What criteria must evidence meet to be evaluated in court?

Evidence must be scientific, sufficient, reliable, and valid.

What did the DOJ and ASA recommend regarding expert witness testimony?

To use objective facts rather than opinions.

What types of evidence can be classified as physical or biological?

Physical evidence includes tangible items, while biological evidence includes materials from living organisms.

What roles are included in a crime-scene investigation team?

Police officers, detectives, CSIs, medical examiners, and specialists.

What are the initial steps first responding officers must take at a crime scene?

Identify the extent of the crime scene, secure it, and segregate witnesses.

What is the purpose of documenting a crime scene?

To ensure that evidence is accurately recorded and preserved for later analysis.

Why is maintaining the chain of custody important?

To ensure that evidence is admissible in court and has not been tampered with.

What technologies have improved crime scene investigation in recent years?

Surveillance cameras, facial recognition programs, drones, and ground penetrating radar.

What is the role of ground penetrating radar in crime scene investigation?

To locate bodies and hidden evidence.

How do drones assist in crime scene investigations?

They map crime scenes and identify/document exact locations of evidence.

What should evidence reports include?

How evidence was compared, limitations, and uncertainty in measurements.

What is the significance of the case study involving the damp, bloody shirt?

It highlights the importance of proper evidence handling and packaging.

What is a common issue with staged crime scenes?

The evidence may not be consistent with witness testimony.

What should be considered when determining if a crime scene is staged?

Type of wounds, victim's profile, and corroboration of statements with evidence.

What happens if the chain of custody is broken?

The evidence may not be allowed in court proceedings.

What is the role of a crime scene sketch artist?

To measure and draw the crime scene to scale, including the position of evidence.

What is the importance of using quantitative and statistical references in evidence?

To ensure that evidence is objective and scientifically valid.

What is the consequence of overstating evidence in court?

It can lead to wrongfully accused individuals being convicted.

What is the consequence of understating evidence in court?

It can allow guilty individuals to go free.