National Park Service investigators found unsafe work practices, violations of federal labor regulations and park policy failure in the death of wildlife biologist Eric York, 37, who was found dead Nov. 2, 2007.

Their report recommended additional supervisor oversight and further safety requirements for handling dead animals.

York -- who was not wearing gloves when he conducted a post-mortem examination of the cougar -- died alone on a couch in his house on the canyon's South Rim sometime between Oct. 31 and Nov. 2 from an advanced stage of pneumonic plague, The (Flagstaff) Arizona Daily Sun reported.

He had been misdiagnosed as having the flu after performing the necropsy on the cougar -- also known as a puma, mountain lion or panther.

A test for flu at a clinic showed negative results, the report said.

York was trying to determine the collared mountain lion's cause of death as part of a project to map the lions' range in the park and educate visitors about them, the Sun said.

The program was temporarily put on hold after his death.

York's supervisor is still employed in the same position and will not be terminated, Palma Wilson, deputy superintendent of operations at the park, told the newspaper.