What are the risk of having a student visa and a work visa that is valid only for 1 year and still in the country after it expires?

I have a "friend" who I basically found out is a very bad person. However, I am hoping for the best. He lies a lot! I was told I can get in trouble if I help him or houses him and he is illegal, but how can I know if they won't tell me? By the way, it seems strange to protect people that are guilty. Anyway, here are the details that I do know of. He came on a student Visa from Libya. He graduated from the university. I believe he then got a work visa and a social security number. He thought he had a year to find work because I believe that is how long is work visa is good for. However, His adviser at the university said he is part of optional practical training which is run by Student and Exchange Visitor Program, and according to their rules he has 90 days to find work in his field or volunteer work of at least 20 hours per week in his field or he must return home. She made it sound like he wasn't illegal though but she wasn't sure. She was going to ask if they come after him and force him to leave. She later said they would not but he isn't eligible for a 17 month extension now. He at first said he was legal to me (after the 90 days) then he changed his answer and said he was illegal, but again, he lies a lot. Lastly, if he isn't illegal now, when will he be? Can he get another visa if he doesn't get a job in a year? He made it sound like because he is Libyan it doesn't matter if his visa is still good. He said there are different rules for Libyans. Also, if he hasn't been informing someone each time he moves, will that prevent him from coming back here or getting another visa or to Canada? Sorry to ask so much but he has made comments about "being dangerous" and "it's so easy to get into the US", so that scares me a bit.