. >> kroft: he's talking about cece moore. genealogy is a small world. she has spent most of the past decade working alone out of her home near san diego helping people identify their birth parents, and putting names on the unknown dead-- a precursor to her latest calling. >> cece moore: when i would be asked, "what do i do?" i'd say, "well, i'm a professional genetic genealogist." and people would just look at me blankly, like, "what is that?" >> kroft: people are just beginning to find out. cece moore is now the lead genealogist for parabon nanolabs, a small d.n.a. technology company in reston, virginia that is leading the way in genetic genealogy. >> the sheriff's office arrested michael f.a. henslick, without incident. >> kroft: the day we visited her, police halfway across the country announced that they had made an arrest on a nine-year- old murder case that she'd been working on. >> moore: this was just this morning, a couple hours ago. >> kroft: where abouts? >> moore: in champaign, illinois. this is the holly cassano murder. she had been stabbed

but now parabon has their new secret weapon, cece moore.'s killer? >> i feel a real affinity to her, and so i'm thinking about her a lot and really keeping her right where i can see her. so, i'm always inspired to work hard on these, but i think it'll make me work even harder, if that's possible. >> it was a no-brainer at that point in time to go ahead and do that. this might truly be the last thing we can do for the case. >> reporter: in the mirack case, there was dna found both on the carpet and christy's body. cece moore and parabon convert that dna into a data file and upload it to a free, no-frills genealogy website called gedmatch designed to find genetic relatives. >> we just need a second cousin, third cousin, or closer to do so. >> reporter: they get a hit. the dna file matches up with several distant family members of the killer. >> i built back to great grandparents for each of the second cousins and then i started building forward. i flipped that tree upside-down, do what i call reverse genealogy. i'm building forward in time, t

>> reporter: enter cece moore, a dna genealogist who started working on cases like christy's with parabon nanolabs. they upload crime scene dna profiles to a free genealogy website called gedmatch, and build family trees to find relatives and zero in on potential suspects. a break in christy's case came in no time. >> i think it took a couple of days. >> reporter: the suspect? raymond rowe, also known as dj freez, a popular fixture in the city for years, charged with criminal homicide. >> they made an arrest. >> reporter: what was that like? >> it was unbelievable. >> reporter: his arrest, one of 11 now credited to this genetic detective. >> if you're going to commit a violent crime like a rape or murder, you're going to leave dna behind. and if you leave dna behind, we can find you. >> this is incredible. much more tonight on "20/20." the dna detective at 10:00 p.m. right here. >>> when we come back, the massive autho recall. >>> >>> to the "index." and the manhunt for a suspect accused in two tennessee murders is now over. authorities closing in on 53-year-old kirby wallace, in the wood