NCJ Number
136543
Journal
Journal of the Forensic Science Society Volume: 32 Issue: 1 Dated: (January/March 1992) Pages: 5-14
Date Published
1992
Length
10 pages
Annotation
This paper explains how single locus DNA profiling may be done to distinguish between the body fluids of full siblings for the purpose of suspect identification from body fluids left at a crime scene.
Abstract
The widespread application of DNA profiling has raised the issue of close relatives sharing body fluid types. In a particular crime case, the defense may suggest that a close relative of the suspect was the person responsible for the crime at issue. This paper establishes a formula for the likelihood ratio, which is then developed in detail for the particular case where the suspect profile has two distinct bands. Generalization to other types of cases is explained, and the impact of the evidence in the context of a trial is discussed. Because of the elaborate calculations involved in distinguishing the DNA profiles of close relatives, the issue should be addressed prior to trial. The case investigator should ensure that any relatives who might credibly be considered suspects be eliminated through the process described in this paper, by taking samples if necessary. If the defense does plan to raise the issue of a relative of the suspect being involved in the crime, then the defense should bring this to the attention of the investigator and thus to the appropriate forensic scientist at the earliest opportunity. 2 tables and 1 reference