The director of the San Francisco Zoo said Thursday that he had overstated the height of the sheer wall in the tiger grotto -- and that the tiger that killed a teenage visitor on Christmas Day may have been able to escape over the walls.
Manuel Mollinedo said the height of the sheer wall in the tiger grotto was 12 1/2 feet, not 18 feet as he previously stated.
Outside experts immediately questioned whether that height was adequate.
But zoo and police officials stressed at a news conference that they still have not determined exactly how Tatiana, a Siberian tiger, escaped from her cage to kill 17-year-old Carlos Sousa Jr. and badly injure two others.
At the news conference with police outside the gates of the closed zoo, Mollinedo also corrected his previous figure for the width of the grotto's dry moat. He said it was 33 feet across, not 20.
Mollinedo said that inspectors from the American Zoological Assn. had not raised concerns about the security of the structure in visits prior to the incident. He said he would invite an association expert to assist in a reevaluation of the site.
The zoo director said the rear doors of the tiger exhibit were secured during the escape.
"My speculation is that the animal came out of that grotto at some location," Mollinedo said. "How she was able to jump that high is amazing to me."
The accreditation organization, which was founded in 1924, said it would wait for a report from the zoo to draw any conclusions. But in a release posted on its website, the association said the incident was the first "visitor fatality resulting from an animal escape at an AZA-accredited zoo."
The zoological association does not specify wall or moat dimensions, but the recommended height is 16 feet -- a 14-foot wall or fence, plus a 2-foot ledge pointed into the enclosure at a 45-degree angle, said Ron Tilson, conservation director at the Minnesota Zoo and coordinator of the association's Tiger Species Survival Plan. He is expected to be the AZA expert who will inspect the tiger grotto.
"I know from personal observation that an adult Siberian male tiger -- a little bit bigger than an adult female -- can step on its hind legs and reach its paw up to 12 feet," Tilson said. "And any cat that can get its paws on a ledge can get up on the ledge."
Asked why a tiger had never previously escaped from the 1940s-era grotto, Tilson replied: "It probably didn't want to."
At the San Diego Zoo, one tiger enclosure uses 12-foot walls on two sides and a 16-foot wall on the third -- equipped with a 4-foot curved barrier at the top that extends inside the enclosure. All the enclosure walls are electrified at the top. In the zoo's Wild Animal Park, tigers are enclosed by a 13-foot fence topped with a 5-foot inward-curved barrier.
United States Department of Agriculture inspectors arrived at the San Francisco facility Thursday to conduct their own investigation of the zoo's animal care, Mollinedo said. The zoo plans to improve the big-cat exhibits, installing new fencing, surveillance cameras and electrified wires.
Contrary to published reports, Police Chief Heather Fong said police had no information to suggest that any of those who were attacked dangled a leg or other body part over the sheer wall, perhaps making it easier for the tiger to climb out.
She said police found a shoe print on the railing of a low fence that separates the grotto from the visitor walkway and that police are trying to determine if the print matches any of the shoes of the three victims. But she denied published reports that a shoe was found beyond the fence, inside the enclosure. The only lost shoe, she said, was found at the Terrace Cafe, about 300 yards from the grotto, where police encountered the two badly injured victims and fatally shot the tiger.
Fong provided some new details of how the incident unfolded.
All three victims were at the grotto when the attack began, she said. When Sousa was attacked, the other two, who are brothers, yelled to distract the tiger. Tatiana released Sousa and turned toward the brothers, injuring one with claw slashes and bites.
The brothers fled to the cafe, but the tiger followed and mauled the second brother there.
Responding to the emergency call, police found Sousa dead near the grotto. After being alerted by zoo staff that the animal was heading toward the cafe, they pursued and found the tiger mauling one of the brothers.
"They saw a victim seated there on the ground. They saw blood coming from his face," Fong said. "They heard him saying, 'Help me, help me.' "
The tiger ignored the police officers' shouts. When a second squad car arrived, Tatiana turned on the officers.
"To protect the victim as well as everyone else, they fired," killing the animal, Fong said.
Nineteen minutes elapsed from the time officers were dispatched to the time the tiger was killed, she said.
Fong said earlier reports that several tigers had escaped were the result of multiple sightings of the same tiger.
The two brothers remained hospitalized in stable condition Thursday at San Francisco General Hospital.
The zoo remained closed Thursday as the investigation continued. The tigers were locked in cages behind the grotto.
"When we open the zoo," Mollinedo said, "the zoo will be safe."
Times staff writer Tony Perry contributed to this report.