CSI Biological and Trace Evidence 3

Question 1

Which of the following best describes the 'touch DNA' technique in forensic biology?

Accepted Answer

DNA extracted from sweat left by skin contact with an object

Answer

Touch DNA refers to epithelial cells shed from skin contact with surfaces, which can yield a low-template nuclear DNA profile.

Question 2

A criminalist finds a fiber with a trilobal cross-section and a distinctive dye absorption spectrum. This cross-section is most associated with which common fiber type?

Accepted Answer

Nylon 6,6

Answer

Nylon 6,6 fibers are commonly manufactured with a trilobal cross-section to improve texture and luster.

Question 3

When documenting a pooled bloodstain, what measurement is recorded to help reconstruct the event?

Accepted Answer

The area, shape, and perimeter characteristics of the pool

Answer

Area, shape, and perimeter features of a pooled bloodstain document the extent and behavior of the deposit for reconstruction purposes.

Question 4

Which type of evidence packaging is most appropriate for moist biological samples to prevent mold and DNA degradation?

Accepted Answer

Paper bag or envelope after air drying the sample

Answer

Biological evidence should be air-dried before packaging in paper, which allows moisture to escape and prevents microbial degradation of DNA.

Question 5

In entomological evidence, the succession of insect species on a body can help estimate the postmortem interval (PMI). Which insect family is typically FIRST to colonize remains?

Accepted Answer

Calliphoridae (blow flies)

Answer

Blow flies (Calliphoridae) are usually the first colonizers of remains, arriving within minutes to hours of death to deposit eggs.

(CSI) Crime Scene Investigator Practice Test

(CSI) Crime Scene Investigator Practice Test

CSI Biological and Trace Evidence 3