There's absolutely no way he wasn't in on it. Someone found out in December, and his family panicked and gave some BS explanation to the school. Nothing adds up here. The chick's picture is of a completely different person, who he supposedly met several times in real life, was his girlfriend for like a year, but she says she never met him.
All we can wait for now is for Te'o to tell everyone whats really going on, because the school's explanation doesn't add up at all. This story is crazy.