I know this is 12 years old topic, but I cannot resist posting in it myself.
I personally know 5 (have at least talked to all):
My own father (not talked to him since I was 2 years old when it happened, but obviously proven that has happened and that he existed). Overdosed on medication.
One who I knew before he was baptized. Had lots of mental issues and he was plain weird. Everyone made fun of him because of that, me included. Now that I look back, maybe I was too rough but who knows what's the real reason, if any. Anyway, he had his own written rules about how things should be done. I was the one who had to take his shit before he got his medication and he found out other people to text to. Obviously didn't figure out his own ways. Jumped off a roof of a building.
One shy guy who married a sister that had a kid. I am in the belief they they either got a divorce or they had some problems in their marriage, thus husband killed himself. Method unknown...
One married guy who was known by basically everybody. Always making fun of either other people or trying to show he's such a cool and fun guy to be around. Jumped in front of a train.
One guy who I emotionally helped after he had gone through judicial committee and he later thanked me for that. Once he bullied me with other witnesses I knew, but I don't hold that against him. He was very nice but mentally ill and ended up killing himself. Most likely overdosed.