Criminalistics: An Introduction to Forensic Science 12e Chapter 3 Review and Critical Thinking Questions

The process of _____ determines a substance's physical or chemical identity with the most certainty that existing analytical techniques will permit

Identification

The number and type of tests needed to identify a substance must be sufficient to ______ all other substances from consideration.

Exclude

A(n) ________ analysis subjects a suspect and a standard/reference specimen to the same tests and examination for the ultimate purpose of determining whether they have a common origin

Comparison

______ is the frequency of occurrence of an event

probability

Evidence that can be traced to a common source with an extremely high degree of probability is said to possess _____ characteristics

individual

Evidence associated with a group, not a single sources, is said to possess _____ characteristics

Class

True or False: One of the major deficiencies of forensic science is the inability of the examiner to assign exact or approximate probability values to the comparison of most class physical evidence

True

The value of class physical evidence lies in its ability to ______ events that data in a manner that is, as nearly as possible, free of human error and bias

Corroborate

The _______ accorded physical evidence during a trial is left entirely to the tier of fact

Weight

Although databases are constantly updated so that scientists can assign probabilities to class evidence, for the most part, forensic scientists must rely on ______ when interpreting the significance of class physical evidence

Personal Experience

The believability of _______ accounts, confessions, and informant testimony can all be disputed, maligned, and subjected to severe attack and skepticism in the court room.

Eye witness

True or False: Physical evidence cannot be used to exclude or exonerate a person from suspicion of committing a crime.

False

True or False: the distinction between individual and class evidence is always easy to make.

False

True or False: Given the potential weight of scientific evidence in a trial setting, failure to take proper safeguards may unfairly prejudice a case against the suspect

True

Students studying forensic science must be cautioned that merely reading relevant textbooks and journals is no substitute for _____ in this most practical of sciences.

Experience

Modern analytical techniques have become so sensitive that the forensic examiner must be aware of the ______ among materials when interpreting the significance of comparative data

Natural variations

True or False: A fingerprint can be positively identified through the IAFIS database.

False

A database applicable to DNA profiling is the FBI's ___________

Combined DNA Index System (CODIS)

The _____ database allows firearm analysts to compare markings made by firearms on bullets that have been recovered from crime scenes.

National Integrated Ballistic Information Network (NIBIN)

The _____ database contains chemical and color information pertaining to original automotive paints.

International Forensic Automotive Paint Data Query (PDQ)

Arrange the following tasks in order from the one that would require the least extensive testing procedure to the one that would require the most extensive. Explain your answer.

a. Determining whether an unknown substance contains an illicit drug

b. Determining the composition of an unknown substance

c. Determining whether an unknown substance contains heroin

1. C

Because you can easily compare the unknown substance to a reference sample of heroin (the search criterion is very specific)

2. A

Because there are many kinds of illicit drugs but there is still a data base of reference samples (search criterion is broader than that of C but still somewhat specific)

3. B

Because you have no reference samples and have to do a lot of testing to even get close to determining what the unknown substance is (no search criterion to help narrow the search)

The following are three possible combinations of DNA characteristics that may be found in an individual's genetic profile. Using the product rule, rank each of these combinations of DNA characteristics from most common to least common. The number after each characteristic indicates its percentage distribution in the population.

a. FGA 24,24 (3.6%), TH01 6,8 (8.1%), and D16S539 11,12 (8.9%)

b. vWA 14,19 (6.2%), D21S11 30,30 (3.9%), and D13S317 12,12 (8.5%)

c. CSF1PO 9,10 (11.2%), D18S51 14,17 (2.8%), and D8S1179 17,18 (6.7%)

a. 0.036×0.081×0.089 ≈ 0.026

= 2.6%

b. 0.062×0.039×0.085 ≈ 0.0206

= 2.06%

c. 0.112×0.028×0.067 ≈ 0.021

= 2.1%

Correct order: A, C, B

Indicate whether the item is more likely to posses class or individual characteristics.

a) An impression from a new automobile

b) A fingerprint

c) A spent bullet cartridge

d) A mass-produced synthetic fiber

e) Pieces of a shredded document

f) Commercial potting soil

g) Skin and Hair Scrapings

h)Fragments of a multilayer custom automobile paint

a. Class Characteristics

b. Individual Characteristics

c. Individual Characteristics

d. Class Characteristics

e. Individual Characteristics

f. Class Characteristics

g. Individual Characteristics

h. Individual Characteristics

Which of the forensic databases described in the text contain information that relates primarily to evidence exhibiting class characteristics? Which ones contain information that relates primarily to evidence exhibiting individual characteristics? Explain your answers.

Individual Characteristics: IAFIS, CODIS

Class Characteristics:

PDQ, NIBIN, IBIS

An investigator at a murder scene notes signs of a prolonged struggle between the attacker and victim. Name at least three types of physical evidence for which the investigator would probably collect standard/reference samples, and explain why he or she would collect them.

an investigator would likely collect standard/reference samples of hair, fibers, and blood because these items are most likely to have been transferred from the perpetrator to the victim, and vice-versa during the struggle.