i skimmed the wikipedia article on him and the tldr is that he studied abroad in china and was allegedly approached by MSS agents who encouraged him to get a job at the state dept or the cia or something in order to pass secrets to them. he accrues like 70,000$ from agents paying him throughout the whole process which ends up being part of the problem because he came back to the US and didnt declare a shitload of cash he was traveling with. then he was arrested and was in jail for 4 years or so.