At least every prosecutor's office has a whole department dealing only with crimes committed by officials, and I guess they're not just sitting around. :-)

I believe it's just like you would expect if you knew nothing about Germany: many crimes are punished, many aren't.

For whatever reason, and yes, cronyism and a certain reluctance to prosecute does happen. But that's a null statement.

I won't claim that reality is great, I just have no reason to believe that police officers regularly get away with major infractions.