He is an authority on the precursors of suicidal behavior.
adjective Of a person, likely to commit, or to attempt to commit, suicide.
After losing his job, his wife, and his leg in a single week, he became suicidal.
adjective Of a voluntarily-chosen course of action, highly likely to certain to result in the deaths of the participants; dangerous or reckless to such a degree as to be tantamount to suicide for those taking part.
adjective Extremely reckless.
His driving habits are utterly suicidal.
noun Someone suicidal; someone likely to kill themselves.