Well, it sounds like a TV show episode, what you're mentioning, but in reality it has happened.
As we've heard, criminals are very smart. They're always trying to stay one step ahead of the law. There have been cases in the U.S. where, for instance, some criminal will provide his DNA sample in some form and will give it to someone to leave at a crime scene. The only way they found out in the U.S. that...because it did match in the data bank. I can't remember what state it was; I'm thinking it was Illinois, but I could be wrong. At any rate, it did match. But when they went back to arrest the person, they realized that the guy had been in jail for the last two or three years. He couldn't have committed the crime.
It turns out that this guy had been selling his DNA samples in little ketchup packets and getting them through the jail for $50 each or something like that. Then at the crime scene, they could sprinkle semen or whatever else he was putting in these ketchup packages.
So it does happen, and that's why DNA by itself shouldn't be the only thing that investigations and convictions rely on. It's only one piece of evidence.
Let's look at exonerating, at being able to exonerate suspects, as they claim. Let's say they run the sample that they find at a party where someone was murdered. It doesn't match up with my DNA in the criminal offenders index. But they have ten other people, including my parents, who saw me at the party and said, “You know what? We saw him stab him.”
Are they not going to follow me any more because they didn't get a hit from the DNA data bank? What does exoneration mean, and how do they use it? Again, statistics without further use of how.... I can't see how any police would give up the trail in that situation just because DNA exonerated me through the DNA data bank.