The History Channel presentation of this is that one of the saboteurs turn in the rest. He was held for the duration of the war and released after it ended.
It would have been an entirely different outcome if they would have eliminated him.
I'm familiar with this story from a book I have about the submarine war off the east coast. I remember it talked about how much chest thumping the FBI did over it, (See, WE ARE ON THE JOB!)
It's in the attic or somewhere, and I don't remember the name of it!