A California coroner says a lion who killed a volunteer intern at a big cat park used its paw to lift a partially-closed door and escape a feeding cage.
Fresno County Coroner David Hadden said investigators believe the lion then attacked and killed Dianna Hanson while she was cleaning a larger enclosure.
The 24-year-old died almost instantly after the lion broke her neck.
Police shot and killed the animal to reach her, believing Ms Hanson was severely injured but alive.
"The lion had been fed, the young woman was cleaning the large enclosure, and the lion was in the small cage," Mr Hadden explained, adding the cage door was partially open, allowing the lion to lift it up with his paw.
"He ran at the young lady."
The coroner added that bite and claw marks found on her body happened after she died, after the lion broke her neck with a paw swipe.
The facility, known as Project Survival's Cat Haven, is normally closed on Wednesdays when the attack happened, and only one other worker was present during the mauling.
The founder of Cat Haven, Dale Anderson, said that he and two other workers had left to take a cheetah to exhibit at a local school.
Ms Hanson was identified by her father, who said working at the wildlife park had been her "dream job", according to the Associated Press.
She had been working for two months as an intern at the 100-acre (40 ha) park, about 45 miles (75km) east of Fresno.
Her father said his daughter had experience at wildlife parks and was "at ease" with big cats, but added that she told him she would not be allowed inside the lion's cage.
The lion was a four-year-old male named Couscous, a California Fish and Wildlife spokesman said.
Couscous had been raised at Cat Haven since he was eight weeks old, said Tanya Osegueda, a spokeswoman for Project Survival.
The project opened in 1993, and has housed numerous big cats, including Bengal tigers, Siberian lynx, jaguars and leopards.