I had a friend from primary school who went to Grammar School (I didn't) who went to prison for armed robbery.
A close relative's ex-wife, when at school, supported another girl's accusations of a male teacher. He was accused of abusing the girl. His wife left him, he lost his job. She was found to have been a serial accuser and her accusations at several schools were all unfounded. My relatives ex-wife is now a police inspector.
I used to have a friend who sold me trout. It turned out that the fish he brought to the house, under cover of darkness, were stolen, from someone's fishing lake, also at night.
I did teach a murderer once, but he was dragged into it by his cousins and uncle. He was walking home from work when his uncle pulled up in a transit van. They attacked a guy coming out of a house (turned out to be the wrong man) with baseball bats. He was the only one in his family in work and had only just left school.