First, no one is a diagnosis. But if your friend does have this, he or she will seem fine until they "break". For example, they may suddenly leave town.

This isn't something for Hacker News and it's certainly not something up for public opinion. If you notice behavior that puts you or someone at risk, contact the police immediately. Otherwise, it's your colleague's personal matter. If you're confused or need someone to talk to more about it, my email is in my profile.