Question 1

A suspect is arrested wearing a torn blue t-shirt. The shirt is collected, packaged in a paper bag and sent to the crime lab. At the crime scene of a burglary an investigator collected blue color fibers from the area near a broken window. The investigator packaged the fibers in a small envelope and submitted them to the lab for comparison to the suspect's shirt. All the tests at the crime lab on the evidence fiber and exemplar fibers from the shirt show them to be identical. Therefore, it can be concluded that the blue fiber from the scene definitely came from a unique source, the torn blue shirt worn by the suspect to the exclusion of all others.

Accepted Answer

While the tests can show that the fibers are identical in composition and color, they cannot definitively prove that the fibers came from the suspect's shirt to the exclusion of all other sources, as there could be other shirts or materials made from the same fiber type and color.

Question 2

Which of the following items would be classified as trace evidence?

Accepted Answer

Trace evidence refers to any small or microscopic material that can be transferred from one location to another, providing a link between a crime scene, victim, and suspect. Safe insulation, glass shards, and soil can all be considered trace evidence as they can transfer between objects or individuals and be used in forensic analysis to establish connections or provide investigative leads.

Question 3

The Locard Exchange Principle occurs with regard to statement evidence being used to corroborate or refute physical evidence collected at the crime scene.

Accepted Answer

The Locard Exchange Principle refers to the concept that every contact leaves a trace, meaning that whenever two objects or individuals come into contact, there is an exchange of materials between them. It is primarily concerned with physical evidence rather than statement evidence.

Question 4

When dealing with a homicide victim's clothing, which of the following procedures is the best way to capture any trace evidence?

Accepted Answer

Examining the clothing for trace evidence prior to transporting the body for an autopsy and collecting any items that are found is the best way to capture trace evidence. This ensures that any trace evidence is not lost during transit and allows for timely analysis by forensic experts. Additionally, allowing the medical examiner to collect the clothing at the autopsy may result in cross-contamination and not fully utilizing the time-sensitive opportunity to collect trace evidence. Removing the clothes at the scene can also cause cross-contamination, and allowing the clothes to fully dry on the body can degrade any biological or chemical evidence present on the clothing.

Question 5

The ____________ exemplars must never be packaged with the questioned samples.

Accepted Answer

Known exemplars are samples taken from a known source, such as a suspect or a victim, and are used for comparison with questioned samples. It is important to never package known exemplars with questioned samples in order to avoid contamination or biasing the examination process.

Question 6

You are responsible for the collection of evidence related to a hit-and-run accident. Choose the proper procedure for collecting paint samples from the two vehicles involved.

Accepted Answer

Collecting two paint samples, one from the accident area and one control, from each vehicle and placing them in separate druggist folds and separate envelopes is the best procedure for collecting paint samples from the two vehicles involved in a hit-and-run accident. This will allow for a comparison of the paint samples using a microscope to determine if they match or not. A control sample is necessary to ensure that any potential matches between the accident area paint and the vehicle paint are not simply the result of the same common color being used on both vehicles. Placing the samples in separate druggist folds and separate envelopes will prevent any cross-contamination.

Question 7

Which of the following techniques would be the best method for collecting fibers found on the floor at the point of entry at a homicide scene?

Accepted Answer

All the mentioned techniques (using forceps, tape lifts, and vacuum) are accepted methods for collecting fibers at a crime scene. Each method can be effective depending on the specific circumstances and the nature of the evidence.

Question 8

When trying to determine the direction of force in glass using a concentric edge, the side of the glass forming a right angle with the conchoidal fracture is the side the force came from.

Accepted Answer

This is true. The concentric edge and conchoidal fracture pattern on glass can help determine the direction of force applied to the glass. The side of the glass forming a right angle with the conchoidal fracture is the side the force came from.

Question 9

Some of the characteristics that a criminalist can provide when examining hair is determining whether it originated from an animal, synthetic, or human; Determine possible body location; or whether it was chemically treated.

Accepted Answer

These are all potential characteristics that a criminalist can determine when examining hair.

Question 10

During a rape the female victim stated that she tore the suspects blue sweater. At the crime scene you recover five blue fibers reported to be the sample the victim ripped from the suspect's sweater. The police arrested a suspect and in the back seat of his vehicle was a torn blue sweater. The items are then sent to the crime lab for comparison. What is the best determination that could be made in assessing if they came from the same single garment?

Accepted Answer

Classification can be used to determine if the fibers are consistent with coming from the same type of garment, but individualization to a single garment is not possible with fiber evidence alone.

Question 11

If you are tasked with collecting computer evidence, which of the following is the most appropriate choice:

Accepted Answer

It is important to not tamper with the evidence until specialized personnel are called in to analyze it. Leaving the equipment in place and consulting with a computer crimes member who is trained to analyze the evidence is the most appropriate choice. This ensures that the evidence is not compromised and can be properly analyzed.

Question 12

Shoes and footwear are valuable items of evidence. In addition to the presence of trace items such as soil, dust, debris, vegetation, and blood the footwear can also be useful in shoe impression comparison and demonstrating directionality.

Accepted Answer

Shoes and footwear can indeed provide valuable evidence through the presence of various trace elements and can also aid in shoe impression comparison and directionality determination.

Question 13

Special care should be taken when collecting items that contain trace evidence on them. Trace evidence from the body may be microscopic and not readily observed such as ____________.

Accepted Answer

Gunshot residue may be microscopic and not readily observed, making it important to collect trace evidence carefully. Bullet wounds, incised wounds, and bruising may all be visible to the naked eye and may not require as much special care during collection.

Question 14

You are tasked with recovering trace hairs and fibers from the exterior of a vehicle that is at the scene of a crime. Which of the following is the most appropriate action?

Accepted Answer

Collecting hairs and fibers on the scene and placing them in a druggist fold, then in a larger envelope, is the most appropriate action because it minimizes the risk of contamination and loss of evidence. This method ensures that the trace evidence is securely packaged and protected until it can be analyzed in a controlled environment.

Question 15

Microscopic examination of the hair root may indicate that the hair was forcefully pulled out as opposed to falling out naturally.

Accepted Answer

When a hair is forcefully pulled out, it often results in the hair follicle being stretched and elongated, causing damage to the root. Microscopic examination of the hair root can reveal this damage and suggest that the hair was pulled out rather than falling out naturally.

Question 16

While investigating a bank robbery you notice that there is significant damage to the vault with cement dust, insulation fibers, and other material throughout the crime scene. You are then notified a suspect was arrested and you respond to the police department to collect evidence from the suspect. You notice similar fibers and dust on the suspect's clothes. Which is the best method to collect the trace evidence?

Accepted Answer

Leaving the trace evidence on the clothing and collecting the entire article of clothing wrapped in butcher paper and placed in paper bags is the best method because it preserves the integrity of the evidence and ensures that all trace material is collected. Scaping the evidence off the clothing could damage or contaminate it, asking the suspect to wipe it onto paper could result in loss or contamination, and wet washing the clothes could destroy or wash away the evidence.

Question 17

Referring to the diagram below, choose the correct sequence of bullet impacts to glass.
 (FIGURE 1)

Accepted Answer

Based on the direction of the impact marks and the circular spiderweb pattern around impact A, it can be inferred that A was the first impact on the glass, followed by B.

Question 18

A piece of duct tape used to bind the victim was recovered and a roll of duct tape was recovered later from the suspects vehicle. In addition to fingerprints and trace evidence that may be on the tape from the scene, a comparison to the roll of tape may be conducted to see if the piece originated from that roll. Which of the following techniques performed:

Accepted Answer

Fracture/tear match is the best choice for comparing the piece of duct tape recovered from the victim to the roll of duct tape recovered from the suspect's vehicle. This technique compares unique patterns or irregularities in the edges of the tape caused by tearing or cutting. If the patterns on the piece of tape match the patterns on the roll, it can be concluded that the piece of tape originated from that roll.

Question 19

When analyzing headlights that are damaged during a hit-and-run vehicle accident there are key characteristics that may provide contextual information about the vehicle at the time of the accident. They are:

Accepted Answer

Analyzing the headlight filament can provide insight into whether the lights were on or off during impact, which can help determine fault. Additionally, examining pieces of the broken headlight can reveal clues about the make and model of the vehicle involved, which may be helpful in identifying potential suspects or witnesses. Therefore, both A and B are key characteristics to analyze when examining damaged headlights in a hit-and-run accident.

Question 20

In a court of law the unique fit of known and unknown fragments of a broken headlight is important for presenting information that:

Accepted Answer

The unique fit of known and unknown fragments of a broken headlight is important for demonstrating a definitive origin of the unknown pieces to known. This can provide strong evidence for linking a particular vehicle to a crime or accident scene.

Quiz 8: Forensic Traces