Most, if not all people who are convicted of a crime have a tendency towards being dishonest and deceitful and it would be in their best interest to try and implicate someone else. Especially if it comes to sex crimes or stealing. I think their DNA should be provided, so after the time has passed and they are released, there are other crimes that are difficult to solve and there is DNA on the site collected by the forensic technicians, but no record of who it belongs to - a sampling of all who have been convicted of prior crimes would show if they were there or not. There are many crimes committed by repeat felons, and having their DNA on file will pinpoint it down to who those people are.