I am not an expert on the fingerprint system, which is run by police and by national sources, but as far as I know, every fingerprint ever entered into the system is kept within the system.
I have been very grateful for this fact on numerous occasions when we had a partly decomposed, unrecognizable, or just plain unrecognized dead body, and the prints came back with a hint: It’s Such and So! Oh, thank God. I recall one particularly grisly case - hm, it’s been adjudicated, so I can talk about it. A man and his live-in girlfriend of many years (nine) were having an argument in their house. Alcohol was involved. He killed her, then decided to hide the crime. Knowing that she had had expensive breast implants many years before that might have serial numbers, he cut off her breasts, and disposed of them.
Somehow.
He never told us how - in fact, he said at one point to the officers, “You’ll never find out where those breasts went”. Two grisly possibilities were suggested by the fact that a filleting knife was found in the sink which had a smear of blood and a streak of dried tissue on it. He might have carved the breasts into small bits and fed them down the garbage disposal. Or, hate to use the word “fed”, there were two large dogs in the house…
He then wrapped the site where the breasts had been in duct tape, removed all her clothes (not necessarily in that order), put her body in the back of his painter’s van, and drove to Washington, DC. He pulled up into the alley behind the place where she had once worked many years before, and dumped the body. He took off. It was found hours later.
Here we were with an unknown, unrecognized, naked body of a middle-aged female, who had been mutilated after death (we could tell it was after death), and who had been partially wrapped in duct tape. It was a grisly sight. We were really afraid we had a serial killer on our hands.
We printed her, and they tried the criminal database. No hits. They tried the military fingerprint database. No hits. Three days into the investigation, they finally got to the massive civilian database. A hit! We identified her! And that told us where she lived and with whom… and the police went out to the house and asked the live-in boyfriend where his girlfriend went and why he hadn’t called her in as a missing person? The lies he told eventually broke down and that’s how we knew it was a domestic violence murder and not a serial.
So I am more often grateful for fingerprints than concerned. I have been fingerprinted myself (condition of applying for a medical examiner’s job in NYC) and my prints are out there in the great civilian database. If I ever turn up naked and mutilated, but still with my fingers on, I expect to be identified.
By the way: Fingerprint databases are searchable because of a complex computer algorithm (here I must bend my head and defer to computer colleagues) which took great efforts by many people to get working. The computer must identify hundreds of points on each fingerprint and compare them to the new fingerprint to declare a match. The new fingerprint is never exactly like the old one (same lines, but always a slightly different angle, and you can acquire scars) and it was really difficult from what I’ve been told to get a program that worked and that worked fast enough. Prior to that, all searches were done by the eyes of an experienced examiner… really slow.
My point is this. I don’t know that DNA is searchable yet. When they take your DNA they either swab the inside of your cheek or draw some blood and squirt it onto spots drawn on the filter paper edge of an identifying card. The cheek cells and/or blood are allowed to dry. Then they go into a huge evidence warehouse somewhere and wait. Your DNA isn’t run (and what would they do nowadays to profile, Antigen? We’re not sequencing people’s full genomes) until they think they need you. So right now DNA databases are not going to convict you of a crime unless they really think you’re worth suspecting in the crime. Like when they take already-run DNA profiles from convicted felons who are in jail for rape or rape-homicide, and compare them to DNA obtained from raped or murdered women.