The title says it all. In 2002, the towering 6'7" rapper Antron Singleton--better known as "Big Lurch"--got high on his drug of choice and went on a murderous rampage, killing & eating parts of his female friend's intestine & lung. The drug was PCP & the victim was 21-year-old Tynisha Ysais. He claims to remember none of it & believes he was on a mission to save the world by "killing the devil before the world ended". He woke up in a psyche ward & received a life sentence for his grisly crime.
While this story cannot be blamed entirely on a drug, it's worth noting that PCP is known for causing manic delirious states & temporary amnesia that can exacerbate mental illness or simply make a bad day much worse. As such, you should stick to a low dose & accept responsibility for whatever you do under its effects BEFORE trying it.
Better yet, just don't try it.