I'm sure it's happened happened at least a few times. The tricky part, then, is to dispose of the body and cover any tracks that might lead investigators to you. This was facilitated by the Reich being corrupt AF. Tell the victim you have meet him on the sly for a tryst and he'll cover his tracks for you.

The right intel, however could lead to the demise of many lives.

We had the flip-side problem here in the States. US sailors would get drunk on leave and blab operational info to German honeypots. The intel would quickly be relayed to the Kriegsmarine and U-boat wolf-packs hunting in the Atlantic would be directed to intercept them. The cracking of the German navy's Enigma codes figured into how the Allies traced the information leaks, and uncovered spies in US ports.