Right, no system is infallible. Knowing that, why gamble with life and death?
Tragic? That is all? Some mother and father lose their child to the illwill of the government and it is tragic?
The tragedy is that it can happen at all. That is what is tragic.
The best we can do is what Damocles said in his post on the topic. Put the convicted in jail for life. If they are exhonerated, release them, ansd compensate them for their lost time. If they are guilty, let them rot. The death penalty is barbaric, and an indication of our lack of sufficient social evolution.
Killing people is not "the best we can do".