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 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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