An autopsy disclosed that Duane Morrison, who held six girls hostage and killed one in the Platte Canyon High School standoff before turning his gun on himself one week ago today, suffered four gunshot wounds, CBS 4 News reports.

Morrison shot Emily Keyes, 16, to death when SWAT officers broke into a classroom where he was holding her and another girl hostage.

Investigators won't confirm if Morrison died from a self-inflicted gunshot wound or from shots by SWAT officers, the television station reports.

The report also says Morrison didn’t have any drugs or alcohol in his system.

It confirms that Keyes died from a single gunshot wound.