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 sexual assault evidence (6) male fraction from sexual assault evidence. 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.
C.	Suspect B is excluded as the source of the evidence, but Suspect A cannot be excluded. Because both bands of Suspect A match those found in the male fraction of the sex assault evidence, A cannot be excluded as a source of the DNA. However, because Suspect B has no matching bands with the male fraction of the vaginal swab, Suspect B can 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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