I agree that it could have been anyone. Police are always held to a higher standard, so I could see where that would be harder to take.
Years ago I had a fiance leave me. I was pissed at the time, but looking back it was the best thing that could have happened. I found many other opportunities and much more pleasure elsewhere. My case didn't last seven years, so I can only imagine how pissed you are.
My vote is to get a hold of his wife and tell her straight up. Chances are the two of them will see each other again and the wife will be super suspicious. Also, his co-workers and/or higher-ups would be interested in this information...