Originally Posted by Rochard

That's not true at all.

My DNA is not in any "system" (at least to the best of my knowledge). So I kill someone, and leave my DNA at the scene. No problem because I'm not "in the system" right? Wrong. My cousin is in the system, or one of my brothers or sisters.

That's how they found the Golden State Killer just recently. He wasn't in the system, but his cousin was. Once they had a blood relative, they just had to narrow it down.