It's more than you think. Google Henry Wade, DNA and innocent. That's just one DA.
rpm don't kid yourself.
allot of these new DNA cases are smoke and mirrors with a twist of lucky fate for the inmates.
they are required by law to test the evidence as used in the trial samples, they are not allowed to collect current fresh samples from the inmate to test.
now knowing that prior to DNA testing in court cases the samples that were originally gathered were tested then stored but the procedure for storage was in no manner as stringent or reliable as those used today. DNA is very easy to contaminate, it only takes a touch with a dirty glove or a dirty petri dish or a million other things that could happen in a not so clean environment. most evidence is stored in a warehouse environment that is open access to anyone that wishes to inspect it. getting a court order for the viewing of evidence in a past trial is not difficult (this excludes drugs guns money ect). tampering or incompetence is a definite risk.
DNA has proved wondrous for the charging and convicting of modern crimes, but it comes at the cost of releasing those who were convicted in the past who have managed a windfall by having their lawyers, family or friends request a viewing and then later requesting a retest of the bodily fluid samples. DNA cannot be accepted for charging a crime but then rejected for appeal purposes.
if you don't believe how easy it would be to do this, file a petition with the court requesting a viewing of the trial evidence in a rape case from the mid to late nineties. use the excuse that you are doing a web based article on a particular type of crime that this one would be relevant to. once you have the court ordered approval in hand go to the DA or the police dept and give them the judges order. they will make you sign for it, then they will give you a box, tell you that you cannot remove any of the articles from the room, and leave you alone to do what you will. some, only a few will actually recheck the box against the inventory after you return it to be sure that all of the articles are present.
now this may have changed recently, but i know it could be done as recently as three years ago here in NH.