I knew multiple people who died by suicide, but none were family members or very close friends. One of them murdered all their family members before they shot themselves. I never noticed any warning signs. However, it's likely that I was just too wrapped up in my own problems to see what's going on around me.
I used to preach to people with trite sayings about suicide being a temporary solution to a permanent problem, and as I became a full-fledged adult, I realized that it was one of the worst things I could say to someone who is suicidal. I still don't condone suicide in any way, and I think that all of those people should not have killed themselves. I also think that the murder part of the murder-suicide was a senseless act of violence. However, I hope that oblivion is preferable to what they were going through before they took their own lives.