I'm sure that VT is telling part of the truth. What we have is a very well educated young man from a good family that appears to be very remorseful for what he did. At some point he made the wrong decision and killed Joanna. The big question, I suppose, is what are the chances that he'll do it again. The prosecutor seems to believe that he is extremely manipulative and calculating, potentially making him a very dangerous man.
I think it's true that he entered Joanna's apartment, attacked her, killed her, put her body in his car, cleaned up, covered his tracks, established an alibi, accused his landlord and did everything he could to get away with murder, while at the same time the fear of being caught was eating him alive.