That's not what that wikipedia article says. Do you have a source backing up your claim? The article says that they have immunity from civil prosecution for cl

That's not what that wikipedia article says. Do you have a source backing up your claim? The article says that they have immunity from civil prosecution for claims arising from procedural abuses in initiating a prosecution and in stating the state's case. That doesn't sound at all the same as "complete legal immunity". By my read of that sentence, if they commit a crime, they are still liable to criminal prosecution - you just couldn't initiate a civil prosecution against them.