This was the UK. No background checks, though it wouldn't have turned up anything. There was no NDA that I remember, and honestly, I don't think the execs would have given a fuck even if they had known, as long as the work got done. I never ratted him out as our manager was fine with his work, and we didn't have a huge overlap of code that we were working on.
Wow, can anyone just do what they want in the UK finance/sw scene? This wouldn't have flied in Germany/Austria. You have to sign extensive NDA's before they let you anywhere near their code/IP.
