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SAN FRANCISCO, Dec 27 (Reuters) - Police are investigating a shoeprint found on the railing of a San Francisco Zoo exhibit from which a Siberian tiger escaped and killed a teenager in a Christmas attack, the city's police chief said on Thursday.

Chief Heather Fong told reporters police want to know if the print matched the shoes of any of the victims, including two brothers who survived maulings, but said there was no indication yet they had incited the 350-pound female cat named Tatiana.

"There is a shoeprint on the railing," she told a news conference. "Our forensic analysis will allow us to determine if any of those shoes match the print that is on there."

"We have no information as of this time from the investigation that tells us that someone's leg was slung over the rail," Fong said.

At the same conference, zoo director Manuel Mollinedo said he believed the tiger escaped its enclosure over a wall nearly 13 feet high, or about three feet below the minimum height recommended by the Association of Zoos and Aquariums.

The wall and a 33-foot moat separate the tiger's enclosure, which dates to 1940, from the public viewing area, Mollinedo said.

"She had to have jumped," Mollinedo said, ruling out an escape by the cat through the back of its enclosure as doors to service areas were locked.

Carlos Sousa, 17, was killed by Tatiana after the caged cat escaped its enclosure. The tiger fatally gashed Sousa's neck and attacked his two friends, brothers aged 19 and 23.

Fong said the brothers fled when they saw the cat had killed Sousa, and the tiger caught up with them about 300 yards away at a cafe on zoo grounds. Police found the tiger there and shot it dead.

The two brothers, whose identities have not been released, were taken to San Francisco General Hospital, where officials said they were expected to recover from their wounds. (Reporting by Jim Christie; editing by Todd Eastham)

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