You're right (I think), so GS could go after him for breach of contract and/or copyright infringement but not any of the criminal offences that were originally

You're right (I think), so GS could go after him for breach of contract and/or copyright infringement but not any of the criminal offences that were originally available to them (including the copyright related ones). Given that their return might be limited to their provable losses & that they'd have to demonstrate those in court I suspect that they'll probably decide it's not worth the effort. The guy has already spent a year in prison after all & they've successfully demonstrated to all their other employees that GS will go for the maximum possible sentence if any of them transgress in the future, which was probably the main point of the whole exercise in the first place.