marezrd- Unit 3: Crime Scene, Physical Evidence and EyeWitness Testimony Review Questions

Define physical evidence.

Any object that can establish that a crime has been committed or can provide a link between a crime and its victim or between a crime and its perpetrator.

List the 3 methods for recording evidence.

Photographs, Sketches and Notes.

The 1st Officer/Responder to the crime scene should do these 3 things.

Call for emergency care if needed, arrest suspect(s) if still at the scene, rope off/isolate the scene

CAD programs are useful in what capacity?

Computer Aided Drafting programs are used to create finished/final sketches of crime scenes.

The successful outcome of a crime scene investigation is almost always directly related to what?

The manner in which the evidence is collected, preserved and analyzed.

The success in the recognition and collection of physical evidence is directly related to what?

The skill/experience of the investigators processing the crime scene.

Explain cross-transfer (think Locard’s Exchange Principle)

When physical evidence is transferred from the criminal/perpetrator to a victim or object due to contact.

Spiral

best for smaller areas and if you are looking for one specific object; start from an exterior location and move in a circular fashion until you reach the center of the room

Grid

most thorough search method; start/end in the same corner; methodically search across and then up/down the crime scene; better for smaller locations.

Line/Strip

 best for large areas; typically used when searching for a missing individual; people walk in a line at the same pace until ready to turn around and walk back in the other direction. 

Quadrant/Zone

large areas are split into different sections; each section can then be searched with different methods depending on what’s appropriate for the location. 

Hit-and-run evidence:

glass, blood, hairs, fibers, tire tracks, etc. 

Arson evidence:

charred debris, flammable liquids containers, fingerprints, etc. 

Homicide evidence:

murder weapon, blood, fingerprints, hairs, fibers, fingernail scrapings from victim, etc. 

What type of packaging is used to collect fingernail scrapings, white powders or other small trace pieces of evidence?

druggist fold

Why are standard reference samples important? 

They are needed for comparison to crime scene samples so you can identify the origin of the crime scene samples. 

What type of container is appropriate to put charred debris from an arson case in? 

Airtight container so volatile chemicals do not get lost in transport to the crime lab.

What type of container is best for blood soaked garments?

Paper bags - allows for air flow, which prevents the growth of mold, bacteria, etc.

What is the official name for a swab taken from the inside of someone’s mouth? 

Buccal Swab

What is the most common type of safety equipment worn by a crime scene investigator?

2 pairs of latex gloves…always. Other pieces of equipment may include shoe covers, tyvek suits, face mask with a respirator. It all depends on the location of the crime scene. 

Which 2 blood borne diseases would be most harmful to an investigator who gets unknown blood on themselves? 

HIV and Hepatitis B

How should infectious materials from a crime scene be handled/disposed of after all evidence has been collected?

After all evidence has been collected, any materials soaked in bodily fluids should be disposed of in biohazard bags (typically yellow bags for linens and red for anything else). The biohazard bags are then disposed of by a biohazardous waste company. 

What do you think the best manner would be for handling fingerprints found in a pool of blood at a crime scene? 

Fingerprints should be photographed first at 3 different angles and also with a measuring tool in the picture for size reference. Once photographed, the print can be lifted with clear tape and placed on a white card. Since the fingerprint is in blood, it is considered to be a biohazard so it should be packaged in a biohazard bag and labeled appropriately. 

Heard in the Supreme Court, which case dealt with the impropriety of the warrantless collection of evidence at a homicide scene?

Mincey vs. Arizona

Investigators are required to have one of these in order to enter/search private property?

search warrant

Name 2 reasons evidence could be deemed inadmissible in court that would fit into topics discussed in this unit. 

Break in the chain of custody; incorrect manner in which the evidence was collected at the crime scene. 

In the Deadly Picnic Lab, what type of reasoning was used to determine who killed Mr. Brooks? 

Deductive Reasoning

Which amendment deals directly with the collection of evidence from a private residence?

4th Amendment

List the 4 reasons when an investigator can enter a private residence without a search warrant.

If in the process of a legal arrest. 

If evidence is in imminent danger or being destroyed (fire, files being shredded). 

If someone is in need of medical assistance. 

If given permission by the parties involved. 

Securing the Crime Scene:

Completed by the 1st Responder(s) to the scene. Ropes, barricades and guards keep unauthorized people out of the crime scene, anyone who enters or leaves is documented.

Separating the Witnesses:

Completed by the 1st Responder(s) to the scene. This is done to prevent witnesses talking to each other before their statement

Scanning the Scene:

Completed by the 1st Responder(s) to the scene. This is a quick walk through, marking evidence with evidence markers.

Seeing the Scene:

Completed by the Crime Scene Photographer. Photos are taken of marked evidence.

Sketching the Scene:

Completed by a CSI. A rough sketch is made of the crime scene to better show perspective and location of evidence.

Searching the Scene:

 Completed by a CSI. This is a more detailed search, using a search pattern.

Securing & Collecting Evidence at the Crime Scene:

Completed by a CSI. Evidence is collected carefully and a log is filled out to start the chain of custody.

rough sketch

will contain all of the physical evidence, a compass pointing north, information about the location of the crime scene and any necessary measurements. 

final sketch

contains all of the items in a rough sketch and is also drawn to scale. 

Describe the chain of custody. 

 list of all the individuals who handle a specific piece of physical evidence. It should include the name of the person, the date and time it was handled and the date/time it was returned to the evidence storage locker. 

individual characteristic

piece of evidence that leads to a single person/origin. Example: DNA

class characteristic

a piece of evidence that narrows down your list of suspects to a smaller group. Example: hair color, blood type 

Why is eyewitness testimony not the most reliable?

Depending upon the circumstances of the crime, it may be hard to remember all the details due to the commotion that occurred or if the eyewitness feared for their own life. The eyewitness may not have been focused on what was going on when it first happened, so what they saw may have been within a short/quick time frame, which makes it hard to remember multiple details. Eyewitnesses have also been known to fill in extra information as a means to be helpful even if they don’t truly remember all of the details he/she is being asked about.  

Describe how an eyewitness can be influenced by the manner in which a line up is conducted and what are some things that should be done to prevent this and other mistakes made by the eyewitness. 

Eyewitnesses often think if they are being called in to do a line up that they suspect must be in there, so they must be reminded that the person they saw may or may not be present. They also can be easily influenced by the line of questioning asked to them or the body language of the person conducting the lineup. To reduce the possibility of the eyewitness being influenced, there should be no talking during the lineup, the person conducting it should not know who the suspect is either, and the eyewitness should look at each person one at a time so they cannot make comparisons between the potential suspects