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.