Not quite murder but a guy in the year below from school took part in a burglary and very brutal assault which blinded a man. He eventually handed himself in and went to prison, where he was attacked and killed inside. He was always a bit of a dick but came from a lovely family so I was surprised. He had young children.
Also, not murder but seen people mention similar, my school was full of pedalos. One teacher took individual photos of all his students, including myself, on the first day of classes each year. He had affairs with multiple students and was later found with thousands of explicit photos and videos of children on his home computer and went to prison. Another teacher was having an affair with a girl in year 11 turned 6th former, his wife also worked at the school. He went to prison as well eventually. Another teacher left his wife for a 6th former and eventually married her but he did also go to prison for it at some point. Another teacher was convicted for having a relationship with a Year 10 student. Most of the PE staff were total p3rv3rts but I think they got away with it. Another of my teachers, who was new, slept with one of my classmates on a night out, not knowing she was a schoolgirl. That was awkward when he walked into our class on Monday morning. These were all male. A female teacher was also convicted for having a relationship with a boy in Year 11 at the time.