A guy that was a couple years ahead of me in school turned into a meth head and killed his dealer and another guy that was at the house, currently doing life I believe.
Another person I went to school with, another fucked up junkie, but this time with a host of mental issues on top of that, went off his rocker and killed two people, attempted to kill a couple more, and robbed and assaulted a couple more, then kidnapped somebody. He got multiple life sentences.
A guy my dad worked with that I met a few times turned out to be a serial killer. He definitely killed 2 people and is the main suspect in 2 more murders, and apparently alluded to there being several bodies that will never be found.