Most of the people suffering with mental illnesses do not commit any crimes but there occur some cases where the criminals have certain mental conditions that are a reason behind the crimes they commit.
Most common mental conditions are
2) Borderline Personality Disorder
3) Antisocial Personality Disorder
Here are some cases of the criminals who have been diagnosed with serious mental illnesses.
But this doesn't mean that behind every crime there is a mental condition. This should be deeply assessed by a competent forensic psychologist.