Yikes. I'm stepping back from, "They got the guy". I saw an interview this morning with a retired FBI agent. She said they identified him not through normal DNA, but through "heritage DNA". In other words, the FBI created a fake account on one of the DNA ancestry sites and submitted a DNA sample*. They then got their hit back that showed all the "DNA relatives" for that DNA sample, and started looking for people related to that DNA group.
That seems really shaky. I did the DNA ancestry thing and first off, they have all kinds of warnings on the kit about keeping your sample pure and fresh (you swab the inside of your cheek and immediately stick the swab in a special container and seal it). They are clear that contamination invalidates results. They're suggesting that the DNA sample came from the body of one of the victims. How did that sample not get dried up and contaminated pretty much right away? I suppose the law enforcement labs are geared to process that, but I question whether the ancestry sites are, especially if the sample is submitted as some John Q Public sample that they assume followed their sampling protocols.
Then when you get your sample back, your DNA relatives are all over the place, like mostly third and fourth cousins. When you get to that point, there can literally be hundreds of people, and that's just people in the company's database. I can't imagine how many third and fourth cousins we all have all over the world.
I mean, given my old job, fed.gov knows everything about me, which is one reason I didn't get paranoid when I did a test at 23andme. This kind of thing though, makes me think about not using these kinds of sites. Especially with LE doing the "fake account" thing. Besides the legal aspect, this sure seems like sloppy evidence collection.
*This might explain why they took so long to arrest someone. I think it took like 30 days for me to get my results. Which is another reason to question why they did this anonymously, instead of as LE, where they could have had the results in 48 hours. Other than they were skirting the law.