The effect of relatives on the likelihood ratio associated with DNA profile evidence in criminal cases.
In DNA profiling sometimes a match is declared between the DNA profile from a suspect and that from a scene-of-crime DNA sample. DNA evidence has frequently been presented in the form of a likelihood ratio, the ratio of the probabilities of the data set under the two hypotheses of a single and two sources for the matching DNA profiles. The calculation of the probability of a match is usually performed using a product rule with information from an appropriate database. This approach has been criticized for failing to allow for genetic relatedness, such that the suspect could be a close relative of the source of the scene-of-crime DNA profile. This paper suggests ways of incorporating the possibility of relatives into the likelihood ratio, and shows that unless there is strong evidence implicating a full sibling of the accused, allowing for possible relatedness has very little impact.
Brookfield
J F
JF
Department of Genetics, University of Nottingham, Queens Medical Centre, United Kingdom.
D003418:Criminology / Q000379:methods*; D016172:DNA Fingerprinting; D005190:Family; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D011336:Probability; D044469:Racial Groups / Q000235:genetics