Genealogy Databases for Criminal Investigations: The Laws Around Using DNA in an Investigation

Dozens of years after the “Golden State Killer” case had gone cold in the state of California, prosecutors utilized a third-party genealogy database to arrest the accused perpetrator – Mr. Joseph James DeAngelo, a former police officer. This astounding criminal case triumph has led many to question the use of sensitive personal information from genealogy databases and websites in criminal investigations, as well as the laws surrounding using DNA such as family members’ saliva as evidence. Here’s what society knows so far.


Paul Holes, a recently retired investigator, led the case involving the Golden State Killer in Contra Costa County. Holes spent the last 25 years working on the case. It was his idea to use a genealogy website to locate the killer. Holes and his team started by reviewing old rape kits with collected DNA samples from the killer’s victims. Police allege that DeAngelo has killed at least 12 people and raped more than 50 others.

The investigators used the DNA from rape kits and crime scenes from the 1970s and ‘80s (the crime spree ended in 1986) to retrieve a breakdown of the unknown killer’s family tree. Investigators narrowed down their search based on the location of the family, age, and other telling characteristics of the killer, eventually identifying Joseph DeAngelo. Then, police officers set up a surveillance of DeAngelo’s home.

They collected DeAngelo’s DNA (without his knowledge or consent) and plugged it into the genealogy database as well. By using the DNA to connect to other relatives, investigators were able to reasonably accuse DeAngelo as the elusive Golden State Killer from almost 40 years ago. Investigators and law enforcement officers have referred to the process as “finding a needle in a haystack,” and “dogged detective work.” Others are referring to the search tactics as unethical.


Arguments against using family members’ genealogical history to track down a killer state that since the family members were unaware the Federal Bureau of Investigation (FBI) was conducting an investigation, it was not ethical for the FBI to use the information. The family members never gave their consent for the FBI to utilize their DNA as part of an investigation or as evidence. Use of the DNA in a genealogy website, therefore, becomes an ethical issue.

Genealogy databases and websites work hard to protect the data and privacy of users. Popular sites such as 23AndMe prioritize privacy, hiring legal teams for just such purposes. Experts on how these sites work say that it would have been close to impossible for investigators to get the mystery Golden State Killer’s DNA into the database, since the quantity necessary is usually a large amount that’s not available at crime scenes. Investigators could, however, access the data downloaded in these databases.

The team that identified the killer used GEDmatch to do so, uploading the killer’s DNA into the database to match the information with family members on the site. GEDmatch commented that it is the company’s policy to open the database for “other uses.” The question of whether the way the FBI found the Golden State Killer is ethical is one for society to answer. The question of its legality, however, lies in state and federal laws.


Currently, it is not against the law to use DNA in investigations or to access public genealogy databases for the purpose of identifying suspects. However, it may be possible to fight for inadmissibility of the evidence collected in certain situations. For example, if a police officer collected evidence without probable cause or consent, a defense attorney may argue that the prosecution cannot use this evidence in a court of law.

Factors may also exist that render the DNA evidence unusable, such as human subjectivity, contamination, or qualifications of lab technicians. Whether DNA evidence gathering is legal depends on the circumstances of the case. Contact a defense attorney for more information about your particular criminal case, and to learn how an experienced criminal defense lawyer can help protect your rights and freedoms.