The Utah state medical examiner has ruled convicted serial killer Roberto Arguelles died from natural causes.
Although Arguelles' death was ruled natural, one of the contributing factors included inflammation of the peritoneum, or the membrane lining of the stomach, caused by ingestion of numerous items.
For the 18 months leading up to his death, Arguelles' bizarre behavior included eating plastic, paper and his own feces, according to documents filed in 3rd District Court. Mostly, he ate a lot of paper, such as his own court documents.
Those dietary habits caused the perforation, and "the natural poisoning of his system took over from there," said Salt Lake County Sheriff's Sgt. Keith Stephens.
Arguelles, 41, died Nov. 15 at the infirmary of the Utah State Prison. Sources who did not wish to be identified told the Deseret Morning News in November that Arguelles had been hospitalized two weeks prior to his death for intestinal problems but refused treatment for a blockage.
Arguelles pleaded guilty to the 1992 kidnappings, sexual assaults and murders of Lisa Martinez, Stephanie Blundell, Tuesday Roberts and Margo Bond. He was scheduled to be executed by firing squad last May but that was put on hold after questions about his competency were raised by prison administrators.