Jack Swarbrick also hired a private investigator firm to look into into it in the last week of December. They reportedly had access to all of Teo's phone and internet records. They would have had to really drop the ball if Teo was behind it.
I don't think Te'o was behind it, but there's no denying he at least led the story on after becoming aware that Lennay Kekua wasn't dead. The timing of events proves it, when coupled with responses he gave in certain interviews when asked about her.
Now, granted, this was probably out of shame, embarrassment, or the least likely scenario - he enjoyed the media attention. And I don't blame him for not talking about it - how do you tell millions of people your dead girlfriend, a story line that heavily bolstered your Heisman campaign, isn't really dead and the whole thing was a hoax? I can't think of an easy way.
If there's one thing that can be learned from this situation, it's this - he's got to be smarter. He's going to have people falling all over him in the next few months/years as he begins his NFL career. If he continues to make trusting mistakes like this, he could be in even more serious trouble.