Glass Evidence Handling Guide

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Questions and Answers

What is the purpose of having the suspect disrobe over paper?

To recover any glass particles that may fall from clothing (correct)

To ensure the disrobing process is more comfortable

To minimize the suspect's exposure during the investigation

To create a clean surface for evidence gathering

What should NOT be used to recover glass particles?

Finger cots

Plastic bags

Tape (correct)

Gloves

What is the primary consideration when submitting glass fragments for physical fitting?

They must be tempered glass fragments

They must only be from the point of impact

They must be large enough for a physical fit (correct)

They must be clean and free of debris

How should larger pieces of broken glass be handled?

They should be marked and packaged carefully to prevent breakage Signup and view all the answers

What is a characteristic of tempered glass when it breaks?

It shatters into thousands of tiny fragments Signup and view all the answers

What must be done to the remaining pieces of glass still in the frame?

Mark them to indicate inside/outside orientation Signup and view all the answers

Why should glass fracture examinations not be conducted from photographs?

The glass must be physically reconstructed for accurate examination Signup and view all the answers

How should broken glass sources be packaged?

Separately from one another and other sources Signup and view all the answers

What should be included when collecting known glass samples at a scene?

Samples from all broken glass sources including multi-paned windows Signup and view all the answers

How should laminated glass be packaged for submission?

Separated and packaged with all layers of the laminate Signup and view all the answers

What is the first step when collecting suspected items from an individual?

Have the suspect disrobe over clean butcher paper Signup and view all the answers

What type of container should NOT be used for packaging broken glass sources?

Paper containers Signup and view all the answers

When collecting questioned items like tools, how should they be packaged?

Placed in a paper bag or secured in a cardboard box Signup and view all the answers

What item should be avoided when packaging clothing from a suspect?

Excessive contact with outer containers Signup and view all the answers

What is a crucial step after collecting hair combings from a suspect?

Secure the comb and debris in a separate paper evidence fold Signup and view all the answers

What should you do with broken glass sources collected from multiple panes of a window?

Package each separately and label appropriately Signup and view all the answers

Why is glass evidence considered valuable to criminal investigators?

It is present in nearly every building and vehicle. Signup and view all the answers

What is the most common request for forensic glass examination?

Comparison of questioned glass particles to a known source. Signup and view all the answers

What types of examinations involving glass may be conducted beyond comparison to known sources?

Direction and sequence of impact determination. Signup and view all the answers

What property can be measured on invisible glass particles?

Refractive index. Signup and view all the answers

What type of conclusion can be drawn when questioned glass properties match those of a known source?

An association may be established. Signup and view all the answers

Which factor is NOT typically compared in forensic glass analysis?

Chemical composition. Signup and view all the answers

What happens to glass particles during a crime when a glass source is broken?

They may be transferred to the perpetrator. Signup and view all the answers

Which of the following is NOT a physical property examined in questioned glass analysis?

Price. Signup and view all the answers

Study Notes

Glass Evidence Handling and Examination Guide

Glass evidence is valuable in criminal investigations because it is commonly found in buildings and vehicles and is frequently broken during crimes.
Glass particles can be transferred to perpetrators and recovered from crime scenes.
The most common forensic glass examination involves comparing questioned glass particles to known broken glass sources.
Other glass examinations include:
- Identifying a material as glass
- Determining the direction of impact
- Determining the sequence of impact
- Identifying the point(s) of impact from a projectile or blow to the glass
The physical properties of questioned glass (color, thickness, tint) are compared to known glass.
Refractive index can be measured on known and questioned glass samples, even on particles invisible to the naked eye.
When questioned glass particles have properties consistent with known glass sources, an association is made, and conclusions are drawn based on the results.

Capabilities and Services

Identification of material as glass
Comparison of questioned glass particles to known glass samples
Fracture matches of glass
Direction of impact determinations
Sequence of impact determinations
Point of impact determinations

Collection Guidelines: Known Glass Samples

Collect samples from ALL broken glass sources at the scene, including all panes of a multi-paned window.
Collect broken glass from the window frame whenever possible.
If laminated glass (e.g., automobile windshields) was penetrated, submit a sample with all layers.
Package each broken known glass source separately.
Package all knowns in a separate container(s) from any questioned items.
Use leak-proof containers (plastic sample jars or plastic bags). Do not use paper or glass containers.

Collection Guidelines: Questioned Items

Package all questioned items separately from broken glass sources.
Collect suspect’s outer clothing and shoes as soon as possible.
Package shoes separately from clothing.
Have the suspect disrobe over a piece of new, clean butcher paper.
Wrap the clothing in the same paper and place into paper bags.
Package clothing and shoes with enough room for removal without excessive contact with the container.
Indicate on the Request for Laboratory Examination form (RFLE) which suspect the clothing and shoes were removed from.
Obtain hair combings using a new, clean comb over a piece of new, clean butcher paper. Submit the paper, comb, and any debris as a separate item.
Collect and submit questioned items, like tools or a baseball bat, wrapped in paper and placed in a paper bag or cardboard box.

Collection Guidelines: Fracture Match Evidence

If a large enough glass fragment transfer occurred, submit questioned fragment(s) and any remaining broken glass from the suspected source.
For hit-and-run scenes, submit all available pieces of headlight and other lamp glass.

Collection Guidelines: Point of Impact/Direction of Impact/ Sequence of Impact Determinations

The broken glass source must be non-tempered.
Submit all larger pieces, including those from the floor, ground, and remaining in the frame.
Mark the glass pieces still in the frame to indicate inside/outside orientation.
Label the glass according to its removal location from the frame (e.g., top, bottom).
Use tape to secure large glass fragments together in a frame.
Package in a manner that prevents further breakage (e.g., heavy cardboard "sandwich" or box with packing material).

Submission Reminders

Do not use tape or adhesives to collect glass.
Submit samples from all broken glass sources at the scene.
Package each broken glass source separately.
Package known glass sources separately from questioned glass sources.

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Description

This quiz explores the handling and examination of glass evidence in criminal investigations. It covers the significance of glass in crime scenes, methods for comparing glass particles, and various analytical techniques used by forensic experts. Test your knowledge on the physical properties of glass and their implications in forensic science.