Even if all that is true, your original statement was:
“It works rather well in Germany, which has no death penalty , but keeps murderers locked up.”
But, in fact, typically, murderers are paroled in Germany, and typically, they serve about as much time as murderers do in the US. Germany doesn't keep its murderers locked up anymore than the US does.
There is no sentence of life without parole. Here is an excerpt from a wiki article:
“The German Constitutional Court has found life imprisonment without the possibility of parole to be antithetical to human dignity, the most fundamental concept of the present German constitution.”
As far as pardoning in the US, it's not very common for a governor (and very rarely for a president, since there are few folks convicted federally of a charge similar to murder) to commute or pardon a murderer sentenced to life without parole, and pardoning folks who have murdered and been sentenced to life without parole is a good way to harm or even end one’s political career.
But you're right - it can happen. A good argument for retaining the death penalty for the worst cases.
On the other hand, German courts can't even hand down sentences of life without parole. Anyone in prison for murder could eventually be paroled.
sitetest
And my original statement is true, I think. Maybe I should have emphasized the certainty of punishment. Germany has many fewer murderers per capita, because Germans are far more rule bound than Americans are, Americans in general. The object is to security the public safety, and the judicial system works better because it is less arbitrary. The roles of officials are better defined, the personnel better trained. So I expect that the parole system works better than ours. The end result is that the average position is more secure in his persons and possessions than we are. At least this the case fifteen or twenty years ago, and even more so before the Wall came down. Whether or not the abolishment of the death system would work in the United States is an open question, but I think the Germans are managing their society quite well without it.