November 01, 2019 Feature

DNA Evidence in Sexual Assault Cases: Past Trends and Future Potential

Cassidy Kesler Pinegar

Genetic genealogy—a combination of DNA testing and traditional genealogical research—emerged as a cutting-edge approach in law enforcement investigations after authorities in California used it last year to identify a suspect in the long-unsolved Golden State Killer case. On April 24, 2018, law enforcement arrested Joseph James DeAngelo, a 73-year-old former police officer believed to be the assailant in a series of murders, rapes, and assaults in California during the 1970s and 1980s. In a last-ditch effort to solve crimes that had been cold for decades, law enforcement entered crime-scene DNA into a public genealogy and DNA database called GEDmatch. The DNA of one of DeAngelo’s relatives was in GEDmatch, leading investigators through familial research to identify DeAngelo as a possible suspect. Law enforcement conducted additional investigation, including surreptitiously obtaining a sample of DeAngelo’s discarded DNA to compare directly to the crime-scene DNA, and ultimately arrested DeAngelo based on the results. DeAngelo has since been charged with 13 serial murders and is suspected to have committed more than 50 rapes. (Paige St. John, Death Penalty Sought for Golden State Killer Suspect, L.A. Times (Apr. 10, 2019).)

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