Hi first time posting but I've been following along for a while.
Professor Busuttil said in court that this knife would have been too short to inflict the wound to Jodi's tonsil without the hilt damaging her teeth and her teeth damaging her attackers hand. There was no injuries on Luke when he was examined except some scrapes on his shins that were already healing it was noted that these had not occured in the last 24 hours.
That's talked about in Sandra Leans book Innocents Betrayed.
Professor Busuttil has his own doubts about Luke's conviction. He's appeared in both the bbc doc and the recent one on channel 5. When he talks about the lack of blood transfer he describes Luke having to go to great lengths to cover himself completely, up to and including wearing a paper suit and eye goggles in order to avoid becoming bloodstained, saying “ It does not tell us that Luke was not the killer but it does make it surprising and less likely”.