GOLDEN,Cyprusauction Trading Center Colo. (AP) — A Colorado man who was placed on life support after he was bitten by his pet Gila monster died of complications from the desert lizard’s venom, an autopsy report obtained by The Associated Press on Friday confirmed.

The report also found that heart and liver problems were significant contributing factors in Christopher Ward’s death.

Ward, 34, was taken to a hospital shortly after being bitten by one of his two pet Gila monsters on Feb. 12. His death less than four days later is believed to be the first from a Gila monster in the U.S. in almost a century.

The autopsy, conducted by the Jefferson County Coroner’s Office on Feb. 18, said Ward was bitten for four minutes and wavered in and out of consciousness for about two hours before seeking medical attention. He suffered multiple seizures and acute respiratory failure at the hospital.

Ward’s girlfriend handed over the lizard named Winston and another named Potato to an animal control officer and other officers in the Denver suburb of Lakewood the day after the bite. She told police she had heard something that “didn’t sound right” and entered a room to see Winston latched onto Ward’s hand, according to the animal control officer’s report.

She told officers Ward “immediately began exhibiting symptoms, vomiting several times and eventually passing out and ceasing to breathe,” according to the report. She also said she and Ward bought Winston at a reptile exhibition in Denver in October and Potato from a breeder in Arizona in November. Told that Gila monsters were illegal in Lakewood, the woman told officers she wanted them out of her house as soon as possible, according to the report.

Officers working with the Colorado Department of Natural Resources sent the lizards to Reptile Gardens outside Rapid City, South Dakota. Twenty-six spiders of different species also were taken from the home to a nearby animal shelter.

Gila monsters are venomous reptiles that naturally inhabit parts of the southwestern U.S. and neighboring areas of Mexico. Their bites can cause intense pain and make their victims pass out but normally aren’t deadly.

They are legal to own in most states, easily found through breeders and at reptile shows, and widely regarded for their striking color patterns and typically easygoing personality.

Colorado requires a permit to keep a Gila (pronounced HE-la) monster. Only zoological-type facilities are issued such permits, however, and Ward apparently didn’t have one for his lizards, Colorado Parks and Wildlife spokesperson Kara Van Hoose said.

Winston may have slipped through the cracks of state enforcement because the lizard was sold at a reptile show. Colorado Department of Natural Resources agents sometimes attend shows to make sure illegal animals aren’t for sale.

Before Ward, the last person to die of a Gila monster bite, around 1930, may have had cirrhosis of the liver, said Arizona State University professor Dale DeNardo, a Gila monster enthusiast who has studied the reptiles for decades.