An Idaho man accused of killing a 70-year-old man is now charged with cannibalism and allegedly said he believed that eating the victim could "cure his brain," according to court documents. 

James David Russell, 39, was already facing a first-degree murder charge in the Sept. 10 killing of David Flaget when Bonner County prosecutors amended a criminal complaint, the Bonners Ferry Herald reported. 

Authorities found Flaget upside down in the passenger seat of his truck with body parts missing and his wrists duct-taped together, prosecutors said. At the time, Russell fled from sheriff's deputies and barricaded himself in a garage but was arrested after a brief standoff. 

IDAHO STATE TROOPER NEARLY RAMMED BY PICKUP TRUCK WHILE HELPING STRANDED MOTORIST: DASHCAM VIDEO

James David Russell, alleged Idaho cannibal

Prosecutors added a charge of cannibalism against James Russell, 39, in the alleged killing of a 70-year-old man. (Bonner County Sheriff's Office)

"There’s a lot of facets we will certainly never know," Bonner County Detective Phillip Stella said last week. "It wasn’t the bloodiest crime scene, but it’s more of the psychological, ‘what the heck is going on here?’ and ‘why am I picking up pieces?’ It’s a walk down the dark path that we don’t see very often."

Investigators also seized a bloodied microwave, a glass bowl, a bloody knife and a duffel bag, the news outlet said. 

Russell allegedly believed that he could "heal himself by cutting off portions of flesh" in order to "cure his brain," court documents said. 

He initially made one statement to authorities, which he repeated, according to the newspaper: "It’s private property and we don’t like non-family on it."

"Flaget had several conflict-like run-ins with Russell and told the family about them," Stella said. "The family had enough warning signs that Mr. Russell was a danger to himself or others."

An autopsy completed on Sept. 13 revealed tissue recovered from Russell's home belonged to Flaget. Some of his remains have yet to be found. 

Bonner County police car, Idaho

  (Bonner County Sheriff's Office )

CLICK HERE TO GET THE FOX NEWS APP

"When dealing with death and carnage it’s a shock to our conscience," said Stella. "As far as I know this is the first cannibalism charge in Idaho."