Speaking of looking for "stolen" code. It can be daunting. For many
years my company was in a love-hate relationship with one of our
competitors. We started out selling their product. We then parted
company and wrote our own. Then we went into joint development for a
couple of years. We then parted company again. Then we went to purchase
them. They sent me up to do due diligence on the company during the
acquisition. It was feared that they had taken code from another
competitor and they wanted me to verify that. Didn't find any evidence of
that, though I did find some verbatim code of mine that they weren't
supposed to have, that was rendered moot by the fact that we were once again
going to be the same company.
For most of the time in my UNIX career, I was working either for the
University or the US Army, so I never had any claim on my code. It went
out on various distributions, and I didn't think much about it. Every once
and a while I'd be surprised when I came across my code in some deployed
system (of all things the NeXT box, for example).