It's something that's being discussed here in the state of Maine as well.
This powerful new tool is providing hope for police and families.
"I hope tomorrow," said Kimberly McLaughlin, whose cousin was murdered. "I hope they call me tomorrow."
It's been a long 38 years for the family of Pamela Campbell.
"Everything was wrong, right from the beginning," McLaughlin said.
The Penobscot County teen was headed to a party in 1981. Police say she never arrived.
"We knew, right then, something had happened," said McLaughlin.
Campbell was found dead a year later.
"That case has been open ever since," said McLaughlin.
Pamela's death is one of 75 homicides in Maine that remain unsolved.
Her cousin, Kimberly is still hopeful.
"They're always trying to solve these crimes," she said. "I have faith that they're trying."
McLaughlin knows a little about searching for answers herself. She's a genealogist, who works to solve mysteries in her family tree.
"It's the challenge, it's the look, it's the search," McLaughlin said of her love of genealogy.
She never thought her passion might be used to find her cousin's killer, until now.
For years in Maine, if police had an unknown DNA sample from a crime scene, they could test it against a state system which housed DNA samples from convicted offenders, known as the Combined DNA Index System, or CODIS.
But according to Alicia Wilcox, a forensic scientist who used to work for the state police, if you've never been convicted of a crime you wouldn't be in the system.
"If you were to commit a crime today and leave your DNA at scene, and never commit another crime again, we would never be able to match you," said Alicia Wilcox, PhD.
They could also test the unknown profile against the federal CODIS data base, where the same rules apply.
Now if there are no matches there, investigators can turn to a new avenue: genealogy databases.
"It's a very powerful tool to be able to look at new suspects we never knew were there in the first place," Wilcox said.
Investigators take unknown DNA profiles from crime scenes and consult private companies, which can compare them to samples in genealogy databases like Ancestry.com or 23andMe.
Those private companies then look for similarities between the suspect's profile and the database, searching for close family members or relatives.
"The databases are huge," said Wilcox. "These genealogy databases are very, very popular. People sending in their sample."
While it might not lead to a direct match, Wilcox says it increases the chances of finding the elusive needle in the haystack when you know which haystack to search.
"A new line of investigation where there was not one before," Wilcox added.
It's a new investigative technique that's yielding results, most notably with the arrest of the alleged Golden State Killer in California in 2018.
Then, the technology hit home, after a southern Maine man was arrested in connection with an Alaskan cold case murder earlier this year.
For McLaughlin, this new use of technology could lead to the answers she and her family have been waiting for.
"If I were given the opportunity to use that voluntary database to catch a scum that murdered someone," said McLaughlin, "I'm all in."
Part II of Chain Reaction will discuss the possible ethical and privacy concerns related to using genetic genealogy to solve crimes, as well as set the record straight when it comes to common misconceptions about the new method.