If you submit DNA to a genealogy website, KIRO 7 discovered law enforcement may have access to the results.
So far more than 5 million people have submitted DNA to search their genealogy on Ancestry.com.
Customers send in a sample of their saliva to companies like Ancestry.com and 23andMe.com.
The websites allow customers to find out where their ancestors came from, and where they settled in the United States.
But we found law enforcement could get access to your DNA profile to solve a violent crime.
Idaho Falls police turned to Ancestry.com to try to solve the cold-case murder of Angie Dodge -- which "48 Hours" investigated.
Dodge was 19 years old in 1996; detectives say the killer left his DNA behind.
In 2014 police decided to try something new, and searched a public DNA database owned by Ancestry.com. When there was a hit, police used a warrant to get the name of the man.
His age didn't match the killer, so they zeroed in on his son, Michael Usry.
Usry was cleared of the crime after his DNA did not match the DNA at the crime scene. The case is still unsolved.
Ancestry.com told us this case is unique because it involved a public database it owned and it has now made that database private.
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We wanted to see if genealogy databases could be used to solve any local cold cases, so we sat down with Pierce County Prosecutor Mark Lindquist.
"As prosecutors we are always going to want DNA -- it is powerful and unique evidence. You're going to get the right person with DNA. We just want to make sure law enforcement has played by the rules and obtained a warrant where necessary before we use that DNA," said Lindquist.
As the popularity of genealogy databases grows, so does the amount of DNA that's available to investigators.
"There are constant advances in DNA technology and this is just another example of how the reach is expanding," said Lindquist.
Privacy statements posted on Ancestry.com and 23 and Me both confirm your genetic profile could be shared with law enforcement if they have a warrant.
A privacy officer for 23 and Me says they try not to make it easy.
"When and if we do receive a request, we'll continue to do everything we can to fight that request and protect the information of our customers," said 23 and Me Chief Privacy Officer Kate Black.
Ancestry.com provided a statement:
"Ancestry understands the responsibility that comes with the trust our customers place in us and privacy is among our highest priorities. Ancestry will not share any information with law enforcement unless compelled to by valid legal process, such as a court order or search warrant. The Usry case was unique. It involved a database we purchased that was an open and publicly available research resource at the time we bought it. After this case, we made the database private to help protect the privacy of our customers. This is also the only formal legal request for DNA related information we have received, as indicated in our transparency reports."
KIRO 7 asked Seattle University law professor Deborah Ahrens about the privacy policies and customer rights connected to your DNA profile.
"Once you've disclosed it, to some extent you've lost control over it," said Ahrens, who teaches criminal law, procedure and evidence at Seattle University School of Law.
KIRO 7 asked if she thinks DNA from genealogy databases is likely to be used against you.
"I don't really think it's a huge additional risk, but I do think it's certainly possible the government could secure your DNA in this fashion and that's something you accept by deciding to investigate your ancestry," said Ahrens.
If customers are concerned and want to delete their DNA profiles, both companies make that possible.
To delete your DNA results on 23 and Me, click here.
To delete your DNA results on Ancestry.com, click here.