ETC Trace Evidence

Question 1

Which principle forms the scientific foundation for trace evidence and states that every contact leaves a trace?

Accepted Answer

Locard's Exchange Principle

Answer

Locard's Exchange Principle holds that whenever two objects come into contact, material is transferred between them, forming the basis for all trace evidence analysis.

Question 2

Which type of microscope is most commonly used by forensic analysts to directly compare hair and fiber evidence side by side?

Accepted Answer

Comparison microscope

Answer

A comparison microscope links two separate microscopes optically, allowing an examiner to view a questioned sample and a known sample simultaneously in a split field of view.

Question 3

What physical property of glass fragments is measured to help determine whether two samples share a common origin?

Accepted Answer

Refractive index

Answer

Refractive index measures how much light bends when passing through glass and is highly consistent within a single production batch, making it a key comparison value.

Question 4

What is the primary limitation of microscopic hair comparison as standalone forensic evidence?

Accepted Answer

It cannot provide the individualization to a single source that DNA can

Answer

Microscopic hair comparison is class-characteristic analysis and cannot definitively identify a single individual as the source; DNA analysis of the hair root or shaft is required for individualization.

Question 5

How should trace evidence such as loose fibers or hair be packaged at the crime scene to prevent loss?

Accepted Answer

In paper envelopes or using a druggist fold

Answer

Paper envelopes and druggist folds allow moisture to escape (preventing mold) while securely containing small loose particles without static buildup that plastic bags can cause.

(ETC) Evidence Technician Certification Practice Test

(ETC) Evidence Technician Certification Practice Test

ETC Trace Evidence