Zoo Director Manuel Mollinedo also said he believes the tiger escaped from that portion of the enclosure, although police said they still do not know what happened.
Mollinedo said the outer wall that separated 350-pound Tatiana from the viewing public is 12 feet 5 inches high -- not the 18 feet he reported Wednesday, and 4 feet below minimum Association of Zoos and Aquariums guidelines for tigers.
Mollinedo said the association inspected the enclosure, built in 1940, three years ago as part of its regular accreditation program and "they never noted that as a deficiency."
"Obviously, we're going to be rethinking that," Mollinedo said. He announced plans to add surveillance cameras, new fencing and an electrified barrier around the exhibit in the wake of Tuesday's escape that resulted in the killing of 17-year-old Carlos Sousa Jr. of San Jose.
The zoo will remain closed today as San Francisco police continue their investigation. Police are trying to determine how the tiger escaped and whether Sousa and his friends, identified Thursday as San Jose brothers Kulbir Dhaliwal, 23, and Paul Dhaliwal, 19, leaped over the railing and taunted the animal.
San Francisco police Chief Heather Fong denied reports that the men dangled a leg into the enclosure or that a bloody shoe was found within the railing.
"We have no information at this point that they did or did not go over the railing," Fong said.
Fong added a few new details of how the attack unfolded. Officers were dispatched to the zoo at 5:08 p.m. The first to arrive went to the tiger grotto, where they saw the dying Sousa lying on the ground in front of the exhibit.
The police chief said it appeared the tiger had attacked one of the brothers first. Sousa and the other brother yelled to distract the tiger, which then turned on Sousa. Fong said the brothers fled toward the cafe, where they had recently bought food, because "they knew there would be people there."
Zoo staff member led police toward the Terrace Cafe, where they believed the tiger was headed, Fong said. In front of the cafe, they saw one of the brothers seated on the ground, his face bleeding, crying "Help me, help me," as the tiger sat nearby. The tiger attacked him again as officers shouted to distract the animal.
Another team of officers arrived from another direction. The tiger appeared to turn on the police and "in order to protect the victim as well as everyone else in the area, they fired," Fong said. It was over in 19 minutes.
Sousa's father, who said the family has hired a lawyer, said Thursday that his son was "a hero" for trying to scare the tiger as it attacked the older friend. "I would do the same," said Carlos Sousa Sr.
In another development, Sousa's father alleged Paul Dhaliwal lied about his son's whereabouts that day. Sousa's family was worried when he failed to turn up Christmas morning to open presents and began calling friends to find out where he was.
Sousa Sr. had called Paul Dhaliwal about 3 or 4 p.m. Christmas Day, an hour or two before the tiger attacks. He wanted his son home to celebrate Christmas dinner with his mother.
But Paul Dhaliwal reportedly told Sousa Sr. that he had not seen his son for days.
"We're just so upset about that," said the victim's cousin, Christina Sousa-Habenicht, 26. "We feel we could have prevented something. We just have this huge 'What if?' -- what if we could have talked to him. Instead his friend lied. What kind of friend is that?"
Ever since the family found Wednesday that Sousa was killed in the attack, they have been trying to reach the Dhaliwals' parents. They have left messages, but the family has not returned their calls. Sousa considered Paul Dhaliwal one of his best friends.
"We have a lot of questions," the teenager's mother, Marilza Sousa, said Thursday. "We want to know how it happened, and only the two boys can tell us."
Police said Thursday that they have spoken to the brothers at San Francisco General Hospital, where they are said to be recovering well from their injuries and are expected to be released within days. But police would not reveal what, if anything, the brothers told them about the tiger attack.
The Dhaliwal family remained behind closed doors at their San Jose home as reporters gathered outside. Court records indicated that Paul and Kulbir Dhaliwal have both been arrested on suspicion of minor offenses this year.
Paul Dhaliwal was arrested on suspicion of being drunk in public March 24 after police say he was drinking beer and smoking marijuana at an In-N-Out Burger on Capitol Expressway. He was sentenced to attend 10 Alcoholics Anonymous meetings.
On Sept. 7, Paul and Kulbir Dhaliwal were arrested on suspicion of public drunkenness. Paul Dhaliwal was also arrested on suspicion of misdemeanor resisting arrest. They have a Jan. 15 court date.
Mollinedo said Thursday that inspectors for the U.S. Department of Agriculture, which regulates zoos and other institutions that publicly display wildlife, will be investigating the tiger escape "from an animal care perspective."
The Association of Zoos and Aquariums said the incident marks the first time an animal has escaped and killed a visitor at one of its accredited member organizations.
Asked Thursday about the zoo's revised dimensions for its tiger grotto, zoo association spokesman Steven Feldman said: "We stand by our statement" Wednesday that the San Francisco Zoo is an "accredited member in good standing" that "has our support at this difficult time."
"Our Accreditation Commission will make a determination once it has all the facts about this incident," Feldman said.
The attack comes as an embarrassment to the nearly 80-year-old zoo, the largest and oldest in Northern California. The zoo was just moving past controversy about the highly publicized deaths of two elephants in 2004 that prompted it to move its remaining elephants to an animal sanctuary.
It also comes as an embarrassment for Mollinedo. The Los Angeles Zoo, under his leadership, was criticized for animal escapes a decade ago. Federal inspection reports indicated that during a 12-month period, a dozen animals at the Los Angeles Zoo escaped from their cages, including a gorilla and a snow leopard.
The San Francisco Zoo is jointly managed by the city of San Francisco and the San Francisco Zoological Society, with a single management structure that oversees animal care, operations, education and public services. Funding comes from admission fees, membership dues, donations and the city.
A six-member Joint Zoo Committee meets monthly at City Hall to discuss zoo attendance, building and maintenance projects, budgets and other issues.
MediaNews staff writers Lisa Fernandez, Mark Gomez, Barbara Feder Ostrov, Kim Vo, Leslie Griffy and Paul Rogers contributed to this story.