The death of Dale Hausner -- one of the two serial shooters who combined to kill six people in the Valley between 2005 and 2006 -- has been ruled a suicide.
According to the Pinal County Medical Examiner, Hausner's cause of death is "amitriptyline intoxication," meaning he overdosed on antidepressants.
Dale Hausner, Serial Shooter, Dies in Prison at Age 40 From "Unknown Causes"
While amitriptyline is most commonly used as an antidepressant, it also is used to treat nerve pain, eating disorders, other mental problems, and preventing migraines.
It's still not clear exactly what happened, as an Arizona Department of Corrections spokesman says the prison system's investigation into Hausner's death is ongoing, so it's not yet clear how Hausner got enough of the drug to off himself.
Hausner was found unresponsive in his cell at the state prison complex in Florence just after noon on June 19 and was pronounced dead at a hospital about an hour later.
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Hausner's urge to die wasn't exactly a secret, as he wrote in a letter to the Arizona Supreme Court last year that he wanted to be "served with my death warrant to be executed as soon as possible."
He was sentenced to death since March 2009, after being convicted of 80 crimes, including the six murders.
Hausner's partner in the serial shootings, Samuel Dieteman, is serving out his life sentence at the state prison in Buckeye.