How is it that everyone involved in the trial isn’t held responsible for their actions in it? If a prosecutor withholds evidence that can exonerate a defendant

How is it that everyone involved in the trial isn’t held responsible for their actions in it? If a prosecutor withholds evidence that can exonerate a defendant who is later convicted and executed, when that evidence comes to light the prosecutor must be charged with the murder of that defendant and put on trial. Chain this all the way down to the beat cops and the technicians doing the lab experiments, and you suddenly have a system of incentives to keep the legal system squeaky-clean honest. Yes, mistakes will happen, BUT THEY’RE ALREADY HAPPENING AND TAKING INNOCENT LIVES. Without “skin in the game”, the legal system is open for corruption, laziness and cut corners.