by Doug Stanglin, USA TODAY

by Doug Stanglin, USA TODAY

The 24-year-old woman who was killed by a lion at a California animal sanctuary was in the animal's cleaning enclosure when it escaped its cage and attacked, the Fresno County coroner's office said Thursday.

The lion apparently used its paw to lift a partially closed door and escape its cage before attacking Diana Hanson.

Fresno County Coroner David Hadden said Hanson died instantly when a 4-year-old male lion named Cous Cous broke her neck. Cous Cous was one of Hanson's favorite big cats at Project Survival's Cat Haven, a 100-acre refuge east of Fresno in the Sierra Nevada foothills.

"The lion had been fed, the young woman was cleaning the large enclosure, and the lion was in the small cage. The gate of the cage was partially open, which allowed the lion to lift it up with his paw," Hadden said. "He ran at the young lady."

Hadden said there may have been a problem with the gate separating enclosures, according to The Fresno Bee.

Hadden also said Hanson was talking on the phone with a co-worker before she was killed. The co-worker grew concerned when the conversation ended abruptly and Hanson didn't call back.

Hanson was lying inside the lion's enclosure when sheriff's deputies arrived. A deputy shot and killed the African lion after another park worker was unable to lure him into another pen. Cous Cous came to the sanctuary when he was 8 weeks old.

Hanson's father expressed no bitterness toward the animal, saying his "absolutely fearless" daughter loved working with exotic cats.

California health officials performed a necropsy on the lion Wednesday and will have results back "in a few weeks," said California Department of Fish and Wildlife spokeswoman Janice Mackey.

"We want to assess the overall health of the animal," she said. "We'll be on site to observe and will also be taking blood and hair samples."

The refuge has no past history of safety violations and is "well run" as far as her department knows, Mackey said.

Paul Hanson, a Seattle-area attorney, said he dropped off his daughter in January to begin a six-month internship.

"It was just a dream job for her," he told the Associated Press late Wednesday, adding that Dianna, from Brier, Wash., hoped to parlay work at the facility into a job with a zoo later in the summer.

He said his daughter had been fascinated by big cats from an earlier age.

"Once there, she gave me the tour and showed me all the big cats there with which she would be working," he said in a statement on Facebook. "Of course, Dianna being Dianna, her favorites were the tiger and the lion, Cous Cous, who killed her today. You can see on her Facebook page all the big cats she loved so much down there."

"Anybody who works with cats knows that they are wild animals and they can turn even on people closest to them. So I always had this horrible, nagging premonition that I would get a call like this," Hanson told ABC News.

"Di, we will always love you. And we will miss you so much. But I know that you will be happy. For now, you truly are in the eternal 'Cat Haven,' " her father said in the statement.

Cat Haven founder and executive director Dale Anderson was crying as he read a one-sentence statement about the fatal mauling at the private zoo he has operated since 1993.

"We take every precaution to ensure the safety of our staff, animals and guests," he said.

A Department of Fish and Wildlife officer told The Fresno Bee that such an attack was "very rare" because of regulations limiting contact between the animals and humans.

Lt. Tony Spada, local warden for the California Department of Fish and Wildlife, told the newspaper that the sanctuary "has a very good history."

"This is a situation where somebody was too close to a lion," he said.

Officials at another big cat sanctuary, Big Cat Rescue in Florida, told the Associated Press last year that at least 21 people, including five children, have been killed and 246 mauled by exotic cats in the United States since 1990. Over that period, 254 cats escaped and 143 were killed.

Contributing: Beth Weise and Michael Winter in San Francisco and Alia E. Dastagir in McLean, Va.; the Associated Press