he did kill himself
heres the death note
"I am depressed ... without phone ... money for rent ... money for child support ... money for debts ... money!!! ... I am haunted by the vivid memories of killings and corpses and anger and pain ... of starving or wounded children, of trigger-happy madmen, often police, of killer executioners ... I have gone to join Ken, if I am that lucky"
ken was his colleague, and they were both a part of "the bang bang club"