Throughout the history of criminal execution, thousands, maybe millions, have died when it was not necessary. I don't know much about the Stanley Tookie Williams case: my point on it is if there is hard evidence to show that Williams did kill the 4 people that he was convicted of killing, then he deserved to die, because even though he repented for starting the Crips, an organization that I think just emulates one of the cancers of this country, he never did admit to the murders. So, he can say he didn't do it, but if hard evidence showed otherwise, its irrelevant. Think: if you were the loved one of those dead people, and you knew that Williams did it, what would you want to happen to him?
However, if there is no hard evidence pinning the murders on him, then he died unjustly. That's my opinion. Convicted killers who mercilessly murdered for greed, passion, or whatever, and where it is clear that they did it with malice, then they deserve to die. The death penalty can most certainly be applied there. But only when it is absolutely clear that the man did it. Did Williams do it? Heck, I don't know. Can someone find out exactly what evidence he was convicted on here?
However, it sounds like that this guy may have been innocent or at least sorry about his crimes, in that case he should at least still be alive. Maybe. I don't know. I need to research this more.