There has been a big freakout over the effects of DNA testing. They thought it would eliminate prime suspects in one or two percent of cases and it turned out to be more like 30 or 35 percent. Given the fact that a prime suspect in a felony usually goes to jail, that translates into some huge number of people sitting around in prisons for stuff they didn't do.
Again, if there's any question, you can maintain public safety by keeping the guy in prison until the question is resolved. You can't unhang somebody.
So how about those cases where there is incontrovertible DNA evidence that the perp is GUILTY?? Do you have a problem with executing THEM??