Updated

A Utah Army veteran charged with killing a police officer and wounding five others in a shootout during a marijuana raid was found Friday hanging dead in his cell, authorities said.

Matthew David Stewart, 39, was found hanging from a bed sheet during a routine cell check just before 1 a.m., Weber County Attorney Dee Smith said.

The county has referred the investigation into the death to an outside agency, and another county attorney will review it.

The man's father, Michael Stewart, has said he doesn't believe foul play was involved and it may have been a suicide.

Michael Stewart said his son was despondent over a judge's recent refusal to hold a hearing on what the family believes was an illegally obtained search warrant.

Stewart was accused of killing strike force agent Jared Francom and wounding other officers when authorities descended on his Ogden home during a January 2012 raid. He could have faced the death penalty if convicted of aggravated murder.

He also faced charges of attempted aggravated murder and marijuana cultivation.

Investigators said they received a telephone tip that Stewart was growing marijuana in his Ogden home about 40 miles north of Salt Lake City. Officers have said they visited when no one was home and believed they could see equipment inside for growing marijuana.

Authorities obtained a search warrant, and a drug task force raided the site on Jan. 4, 2012.

Stewart maintained he never heard the officers identify themselves and believed he was being robbed when they broke open his door with a ramming device.

Police said Stewart had not responded to a knock at the door and waited for police to enter before firing into a hallway from his bedroom.

During the gun fight, Stewart suffered several gunshot wounds and was hospitalized for nearly a month.