Three recent cases have highlighted a fascinating discipline assisting law enforcement in generating leads for both current and decades old investigations. “Forensic” or “Genetic Genealogy” can link suspects to crimes through DNA, using family tree connections with both living relatives (they’ve likely never met) and deceased relatives dating back hundreds of years.
CeCe Moore, Chief Genetic Genealogist at Parabon Nanolabs and founder of DNA Detectives, has assisted law enforcement in solving over 250 cases to date. While she didn’t assist on accused Idaho murderer Bryan Kohberger’s case, she explained how he was likely linked to the 2022 murder of four University of Idaho students using a combination of DNA tracing, genealogy, and investigative work.
(Smith, Daily Mail US, 2023) . Moore also stresses however her type of work is only a “lead generator” and not actual evidence to be presented in court.
When a crime is committed, it is nearly impossible for an offender NOT to leave trace DNA evidence at the scene. Even when wearing gloves or other protective clothing it is likely that DNA will be left behind, and the more violent the crime, the more likely DNA will be transferred. Once law enforcement recovers scene DNA they will build a DNA profile using “Short Tandem Repeat” or STR comparison. STR looks at twenty DNA markers, which is enough for identification if a person is already in the system or an immediate relative (parent or sibling) is in the system. (National Institute of Justice, “What Is STR Analysis?,”, 2011) If no match is found, a wider search for more distant relatives must be conducted.
This is where genetic genealogy testing enters the picture. Genealogy companies (for example Ancestry, 23 and Me, My Heritage, etc) can search up to 1 million DNA markers using a method referred to SNPS, which differs from STR. This creates a much wider pool of distant relatives to connect to. Currently only two DNA genealogy companies, GEDMatch and Family Tree DNA, openly allow law enforcement access to their databases; and even though they are among two of the smallest companies, their records contain information on approximately 2 million people. (Smith, Daily Mail US, 2023)
Often the list of potential relatives could contain hundreds or even thousands of people who share only a small amount of DNA. From there investigators will look for commonality or patterns; one person related to all those people at the top of the list; what and more importantly WHO they have in common, and from their work forward building a family tree. This can be a complicated and arduous process given that public records past the 1950 census are scarce. Investigators utilize whatever information they can, including birth and death certificates, newspaper articles and announcements, cemetery records, and so on. As they approach present day the job gets more difficult (due to the sheer number of
descendants) so investigators also turn to social media and information aggregation websites such as whitepages.com, beenverified, and ussearch.
As the process continues investigators will narrow in on a suspect. They may arrive a generation or two away (parents or grandparents) and then utilize additional factors to eliminate people and narrow the search further. Factors such as age, gender, location, occupation, vehicles owned, etc. will help them
determine the prime suspect.
Once identified, investigators will conduct surveillance on the suspect and attempt to secretly collect a DNA sample to directly compare to the DNA recovered from the initial crime scene. In the Idaho case of Kohberger, police recovered DNA from a knife sheath left by the killer at the scene. Using forensic genealogy, they traced the DNA to a distant relative Kohberger likely never met or even knew existed (e.g. 3 rd , 4 th , or even 5 th cousin). Investigators worked backwards to identify a common relative, then forward again building a family tree, and narrowed in on Kohberger, who lived in the area and drove a vehicle matching that of the suspect vehicle. In the case of Kohberger’s DNA match, investigators have said the recovered sheath DNA is 5.37 octillion (1 follow by 27 zeroes) more likely to be his than a random person’s. This method of investigation is not without criticism or controversy. Kohberger’s
defense team has raised objections about the warrantless recovery of the DNA used to match (from a discarded Styrofoam cup) as well as the reliability of genealogy website DNA information. A critic of the use of this science, Dr. Leah Larkin, is cited in an affidavit claiming she is aware of cases where genetic
genealogy was wrong and questions law enforcement’s use of the data bases. (Poleo, 2023)
Despite criticism of the science, DNA and Forensic Genealogy are valuable tools to assist law enforcement in generating leads and resolving decades old crimes. Two recent examples of cold case arrests illustrate this usefulness. Kurt Rillema, a married father and owner of a successful construction business, was arrested in a pair of nearly 25 year old sexual assaults. Parabon Nanolabs was able to match a DNA sample from the crime scenes to a sample in GEDMatch and identify common relatives dating back to the 1700’s. From there investigators built a family tree, and narrowed the suspects to Rillema and his two brothers. From there investigators were able to zero in on Rillema who resided in the area at the time of both rapes, one in Michigan and one is Pennsylvania. (Rosenberg, 2023) Finally, a NJ attorney Matthew Nilo was identified using Forensic Genealogy as the suspect in a series of Boston area sexual assaults dating back 15 years (’07, ’08). After narrowing in on Nilo as a suspect, Investigators obtained samples of his DNA from silverware and a drinking glass he used at a corporate event and discarded. Nilo, now 35 years old and engaged, has been charged in 8 total sexual assaults. He has been suspended by the law firm where he worked prior to his arrest. (Smart, 2023)
Because forensic sciences are always evolving, criminals will never anticipate future ways in which they may be identified and charged. A rapist 25 years ago had no idea that investigators one day would be able to trace him using DNA a distant relative (he does not even know exists) decided to submit to discover where they came from and who they are related to. Yet the reality today is we have this and other tools at our disposal to assist in solving cases when we have nowhere else to turn.
