With reference to the part I bolded, if that is the case, why not stick with the same story right from the begining, show remorse, explain what happened, leave no detail out, call paramedics, have some proof, go to trial end of story. If a person is telling the truth, the information is the same no matter how many times you tell it. A body doesn't just disappear without assistance.
Get on with your life, go to University, prove yourself, get a decent job, and maybe just maybe someone would have believed him. His futher path of destruction in the last 5 yrs, only solidifies he was responsible for NH death, IMHO. To top it off, he contacts the mother of the deceased for money in exchange for information.
The more I read, the more I think, JMHO, he doesn't know what happened to the body because his father took care of it. Shortly after his father passes away, he tries the extortion. He had 5 yrs to try it. Is this because his father isn't alive and he's the only one that knows what happened to NH's body? or he knows exactly what happened to NH's body, however he thinks he can have the upper hand. During the 5 yrs, he consistantly spoke about NH to other people, changing the story time and time again.
If he was telling the truth from the begining, IMO, he wouldn't have to keep changing the story.