Suicide

Suicide is a common cause of death.

Description
Suicide is the act of killing one's self, generally as result of depression or having done a bad deed (such as murder; in this case, it would be known as a murder-suicide case). Many spirits who have commited suicide have found some way to communicate to the living that suicide is not a good way out, as you are forced to spend eternity wandering (unless they crossover into the afterlife).

Trivia

 * Almost 30% of all hauntings are result of suicide.