Its kinda sad but the other two guys were deranged, it seems Mark Dixie did his shit just purely for sex reasons. Heres a photo of him and the girl he killed:
http://news.bbc.co.uk/1/hi/england/london/7254628.stm
His spunk was found on a newspaper cutting about Sally Ann's murder which was found at his flat:
http://www.express.co.uk/posts/view/35805
What a fucker.
Crime in the UK is a serious problem but thankfully the UK at least has a good justice system and a decent record of catching the bad guys. He was caught when he got involved in a fracas in a pub and they took his DNA and of course it matched with DNA already recorded at the crime scene.