DNA
DNA typing tests with the standard 13 STRs linked fi ve murders and rapes in the Baton Rouge, Louisiana, area that occurred over an 18-month period. Based on an eyewitness report that a white male was seen leaving one of the crime scenes in a pickup truck, a police dragnet was initiated to collect DNA samples from more than 1000 white males in the area. However, the dragnet and seven long months of investigative work failed to fi nd the culprit. The police then turned to DNA Print Genomics Inc. (Sarasota, FL) to perform a genetic test with single nucleotide polymorphisms (SNPs) to predict the ethnic ancestry of the biological samples obtained from the crime scenes. The DNA Print test revealed that the samples came from a person who had 85% African American ancestry and 15% American Indian ancestry. Authorities turned their attention to black males and within 2 months arrested Derrick Todd Lee, an African American resident in the area with an extensive criminal record. Confirmatory testing with the standard 13 STRs matched Derrick Todd Lee’s DNA profile with the ones found at the crime scenes. In the future, this type of analysis to predict ethnicities and even phenotypic characteristics of perpetrators may be used in conjunction with DNA intelligence screens (see Chapter 12) to help narrow the list of possible suspects. Currently SNP tests, like the DNA Print assay, consume too much DNA material to be used routinely on precious crime scene samples. More validation studies will be needed in the future before such ethnicity tests become widely accepted.
Source: Frudakis , T. N. ( 2008 ) . Molecular photo fitting: Predicting ancestry and phenotype using DNA (pp. 599 – 603) . San Diego : Elsevier Academic Press
DNA