DNA Forensics Problem Set

DNA Forensics Problem Set 2

Problem 8: Another rape with two suspects

The key portion of the autoradiograph from a single locus probe analysis of various DNA samples in a rape investigation is shown in the figure.

The DNA samples are as follows:

(1) known blood sample of victim
(2) known blood sample from Suspect A
(3) known blood sample from Suspect B
(4) DNA size markers
(5) female fraction from vaginal swab of victim
(6) male fraction from vaginal swab of victim.

If you are the DNA analyst, you should conclude that:

A. Both Suspects A and B are excluded as the source of the evidence.

B. Suspect A is excluded as the source of the evidence, but Suspect B cannot be excluded.
The male fraction of the evidence has alleles that are not consistent with A's profile. However, the evidence had two bands that match Suspect B's profile, implicating Suspect B in the crime.

C. Suspect B is excluded as the source of the evidence, but Suspect A cannot be excluded.

D. Neither Suspect A or B can be excluded as a source of the evidence.

E. Suspect B cannot be excluded as a source of the evidence. The results with Suspect A are inconclusive.

The Biology Project
University of Arizona
Tuesday, August 20, 1996
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