Carla Walker. Christine Jessop. Siobhan McGuinness. For years, these victims were listed on cold case files in law enforcement evidence boxes. While never forgotten, limitations in forensic science prevented their cases from being closed. Families waited decades for answers and justice while their killers remained unidentified.
To generate leads in criminal cases investigators traditionally upload DNA profiles found at crime scenes to CODIS, a DNA databased maintained by the FBI. As of September 2020, CODIS has produced more than 533,268 hits assisting in more than 521,562 investigations. Yet, CODIS has its limitations. In order for a hit to a known identity to occur, the offender profile must already exist within the DNA database. For the families of Carla, Christine, and Siobhan, no such matches were found.
In 2018, a new tool for crime solving rose to prominence as the notorious Golden State Killer was finally unmasked. For years, Joseph James DeAngelo remained under the radar until investigators in the case partnered with genealogist Barbara Rae-Venter. Using genome-wide testing to generate a comprehensive DNA profile, the team turned to a genetic genealogy website where users came to learn more about their roots - GEDmatch.
GEDmatch contains DNA profiles from users who had taken tests from direct-to-consumer companies like Ancestry and 23&me. The platform serves as a place where users can upload their DNA data files to compare their genetic relationships with others to build their family trees. It’s also been an invaluable resource for a new technique called forensic genetic genealogy.
Forensic genetic genealogy relies on genetic relationships between a DNA profile for an unknown person and profiles of known people in genealogy databases, such as GEDmatch, FamilyTreeDNA, or DNASolves. To begin, investigators upload their unknown DNA profile to the site, which generates a list of the closest genetic matches, based on how many centimorgans (cM) of DNA are shared with the unknown person. Next, investigators will begin to build back the unknown person's family tree until a common ancestor is uncovered. Then, they will build the family trees forward, identifying every descendent possible, using traditional genealogy techniques. Once the trees have been fully built out, investigators look to identify candidate persons that might match the unknown person. Once a person of interest has been identified, new DNA can be collected to compare to the original forensic sample.
After 46 years, through a combination of advanced DNA testing, forensic genetic genealogy and traditional detective work, the Fort Worth Police Department was able to indict Glen Samuel McCurley for the 1974 death of Carla Walker. Using similar methods, Christine Jessop’s killer, Calvin Hoover, was identified. Christine was 9 years old when her life was cut short in the small town of Queensville, Ontario. It took 36 years to close the case. In Missoula, MT, investigators were able to determine that it was Richard William Davis who killed 5-year-old Siobhan McGuinness.
This case took 46 years to close and it now appears that the killer of Siobhan may also have been involved in other unsolved crimes.
ISHI is excited to announce our new video series in collaboration with Othram that will showcase the important work being done behind the scenes to solve these cases. We’ll meet the analysts performing the DNA work, investigators, victim advocates, and may even speak to family members of some of the victims to hear how forensic genetic genealogy is transforming how cold cases are investigated. For years, these killers escaped justice; maybe forensic genetic genealogy really was the missing piece.