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Authorities trying to determine what caused a lion to maul and fatally attack a female intern volunteer at a private wild animal park in California say the 24-year-old died quickly of a broken neck.

Fresno County Coroner David Hadden says Dianna Hanson was already dead when the 550-pound lion was tossing her body about its enclosure shortly after the Wednesday afternoon attack.

But Hanson was apparently not inside the lion's cage; rather she was in a large play or exercise area. The lion escaped from its cage into that area where it fell upon her and killed her, Hadden tells Fox News.

Hadden says Hanson was cleaning an enclosure when investigators believe the lion may have used its paw to lift a partially opened door of a smaller cage, but the investigation continues.

Authorities said she was talking with a co-worker on the phone in the moments before she was killed. When the conversation ended abruptly and Hanson failed to call back, the co-worker became concerned.

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Hadden said Thursday that bite and claw marks found on Hanson's body were sustained after she died. He said investigators believe the lion broke Hanson's neck with a paw swipe.

Q13 Fox reports the Seattle native was identified as the victim of the attack by her father, Paul Hanson.

"Please honor Dianna's memory by helping her favorite cause: preserving the remaining big cats in the world," Paul Hanson said in a statement. "She would ask us to do that for her."

Paul Hanson said his daughter was thrilled to begin her six-month long internship, and that she frequently posted pictures of the animals on her Facebook page, including the lion that killed her. Hanson said she hoped to work at a zoo after the internship ended.

"She was at ease with those big cats," Hanson said. "They liked her."

The victim was attacked and killed when she entered the lion's enclosure, Cat Haven founder and executive director Dale Anderson said. Anderson was crying as he read a one-sentence statement about the fatal mauling at the exotic animal zoo he has operated since 1993.

KMPH reports deputies shot and killed the lion, a 4-year-old named Cous Cous that has been raised at Cat Haven since it was 8 months old, in order to provide medical attention to Hansen.

Sheriff's deputies responding to an emergency call from Cat Haven, in the Sierra Nevada foothills about 45 miles east of Fresno, found the woman severely injured and still lying inside the enclosure with the lion nearby, Fresno County sheriff's Lt. Bob Miller said.

Investigators were trying to determine why the intern was inside the enclosure and what might have provoked the attack, sheriff's Sgt. Greg Collins said. The facility is normally closed on Wednesdays, and only one other worker was there when the mauling happened, Collins said.

Cat Haven is a 100-acre facility just west of Kings Canyon National Park. Since the property opened in 1993, it has housed numerous big cats, including tigers, leopards and other exotic species. It is permitted to house exotic animals by the California Department of Fish and Wildlife and is regulated as a zoo by the U.S. Department of Agriculture.

Results of the last 13 inspections by the Department of Agriculture's Animal and Plant Health Inspection Service show no violations dating back to March 2010. The most recent inspection was Feb. 4, USDA records show.

Despite state regulations that require annual inspections, the California Department of Fish and Wildlife most recently inspected the facility in January 2011.

"We have to do the best we can with the resources we're provided," said department spokeswoman Jordan Traverso.

The inspector's written comments were "facility in good condition." The inspector checked gates, enclosures, water supplies, drainage, cleanliness, ventilation and the general health of the animals.

Department spokeswoman Janice Mackey said she was unaware if any state regulations would prohibit an employee from entering an exotic animal's enclosure.

She said each species is identified on the permit, and the animals must be used for scientific or educational purposes only.

"We don't allow them to be used as pets," Mackey said.

Actress Tippi Hedren, who founded the Shambala Preserve in Southern California, home to 53 seized or abandoned exotic pets, expressed dismay over the killing of the lion.

"It wasn't the lion's fault. It's the human's fault always. I've got 40 years behind me. I know what I'm talking about," Hedren said.

A movie was made at Shambala several years ago and several people were injured. "Two were nearly killed," she said.

"Lions are one of the four most dangerous animals in the world. There is nothing you can do. When they get a thought pattern, there is nothing short of a bullet to the brain that will stop them," Hedren said.

Nicole Paquette, vice president of the Human Society of the United States, voiced similar concerns.

"She should have never been in the enclosure with him," Paquette said of the victim. "These are big cats that are extremely dangerous, and they placed a volunteer in the actual cage with a wild animal. That should have never happened."

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

Tatiana, a tiger at the San Francisco Zoo, was killed by police after jumping out of its enclosure and fatally mauling a 17-year-old boy and injuring two other people in 2007.

Cat Haven has housed Bengal tigers, Siberian lynx, caracals, jaguars and leopards of various types as well as bobcats native to the area. Anderson described the private zoo several years ago as one of a handful of facilities across the U.S. that has all of the big cat species in one place.

The facility's website says it promotes conservation and preservation of wild cats in their native habitats and offers visitors tours and educational outreach.

Anderson said Project Survival would investigate to see if the intern and the other worker who was on-site followed the group's protocols.

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

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The Associated Press contributed to this report.