Deck 14: Forensic Chemistry and Trace Evidence Analysis

Question 1

An analyst receives a small paint chip from a hit and run case. A part of testing, they obtain an FTIR of one of the layers. The spectrum will most likely reveal

A) specific chemical identification of compounds in the paint
B) the company that made the paint, when they made it, and at what factory
C) class characteristics of the paint
D) the make, model, and VIN number of the vehicle it came from
E) none of the above

Answer 1

C

Question 2

A physical match of two pieces of physical evidence

A) often provides definitive linkage of the two
B) always proves that they are from the same source
C) eliminates Q as K
D) means nothing
E) none of the above

Answer 2

A

Question 3

Physical characterization of a piece of trace evidence, such as plastic from a plastic trash bag, includes all of the following except

A) Raman microspectrophotometry of the surface
B) microscopic examination of the the surface texture
C) measurement of the thickness of the plastic
D) layering of the polymer layers
E) none of the above

Answer 3

A

Question 4

Chemical characterization of a piece of trace evidence, such as plastic from a plastic trash bag, includes all of the following except

A) UV-VIS microspectrophotometry
B) measurement of striations in the plastic
C) Elemental analysis using ICP-MS
D) GC-MS of an extract of the plastic
E) none of the above

Question 5

A green wool fiber is recovered from a blanket used to cover a homicide victim found in a shallow grave. The investigation leads to a suspect and green fibers are collected from the carpeting in the truck of the suspect's car. The analyst uses FTIR, UV-VIS, and microscopic examination to compare the two samples (Q vs K). All of the following are potential results except

A) Inclusion - the fiber from the victim could have come from the car
B) definitive proof that the fiber from the victim came from the car
C) exclusion - the fiber could not have come from the car
D) indeterminate - more fibers would be needed to characterize within sample variation
E) none of the above

Question 6

Which of the following is not an example of an acquired characteristic of paint on a door?

A) sun bleaching
B) scratches
C) mold stains
D) cracking due to dryness
E) none of the above

Question 7

An analyst collects UV-VIS spectra from several locations on the surface of a tape sample. This information will aid in characterizing

A) within sample variation
B) between sample variation
C) incongruity of stratification
D) conglomerate variation
E) none of the above

Question 8

Analysis reveals that a fragment of duct tape has two layers, a fibrous backing with a criss-cross pattern, a nylon-based adhesive, and a semi-tacky adhesive. This information arises from the process of

A) measuring between sample variation
B) individualization
C) successive classification
D) measuring within sample variation
E) none of the above

Question 9

Successive classification can lead to which outcomes?

A) inclusion
B) exclusion
C) indeterminate
D) all of the above
E) none of the above

Question 10

An analyst performs a color test on a suspected drug sample and reports that a purple color results. This is a/an

A) quantitative description
B) subjective description
C) objective description
D) relative description
E) none of the above

Question 11

Humans have cells in the retina that are sensitive to three ranges of color which are

A) red, green, and blue
B) black, white, and grey
C) purple, red, and yellow
D) yellow, green, and cyan
E) none of the above

Question 12

Color receptors in human vision correlate to _____ in the CIE system

A) LAB values
B) tristimulus values
C) hue, saturation, and depth
D) observer angle
E) none of the above

Question 13

The key reason for using the CIE and related systems in forensic applications is

A) to remove objectivity from color analysis
B) to remove subjectivity from color analysis
C) to improve the spectral resolution of the data
D) to make it possible to use microspectrophotometry
E) none of the above

Question 14

What is an additive color system?

A) One that becomes more intense with changes in hue
B) One that becomes less intense with changes in hue
C) One in which the primary colors can be combined to create other colors
D) One that can be combined with other basic spectral colors
E) none of the above

Question 15

Chromaticity coordinates are used to

A) plot spectral data points in three dimensions
B) reduce the dimensionality of large data sets
C) calculate the difference in colors in three dimensions
D) plot data points describing color in two dimensions
E) none of the above

Question 16

The following is a spectrum in the VIS range.

If this is a reflectance spectrum, what is the best description of the color?

A) purplish
B) yellow-orange
C) red-pink
D) blue-green
E) none of the above

Question 17

The following is a spectrum in the visible range

If this is a transmittance spectrum, what is the best description of the color?

A) green
B) blue-indigo
C) orange-red
D) red-pink
E) none of the above

Question 18

Why are CIE LAB coordinates used more often in forensic applications than chromaticity coordinates?

A) it is easier to implement
B) the color space is symmetrical
C) it does not require a spectrum
D) it is subjective rather than objective
E) none of the above

Question 19

What differentiates a dye from a pigment?

A) solubility
B) presence of a nitrogen group
C) absence of a nitrogen group
D) conjugation
E) none of the above

Question 20

Why is it important to characterize several locations on a fiber or fibers?

A) to define between sample variation
B) to refine the exclusion probability
C) to refine the inclusion probability vector
D) to define within sample variation vector
E) none of the above