SAN FRANCISCO -- Reports are surfacing that Paul and Kulbir Dhaliwal, the two brothers who survived the Christmas day tiger attack at the San Francisco Zoo, have been less than cooperative with the SFPD as the investigation into the attack continues.

Authorities say Paul Dhaliwal, 19, and Kulbir Dhaliwal, 23, initially refused to give their own names or identify Carlos Sousa Jr. as the other attack victim. They also would not give an account of what had happened at the zoo to police.

During interviews with media Thursday, Sousa Jr.'s father also revealed that he had called the younger Dhaliwal brother while trying to figure out why his son hadn't been at Christmas dinner. Even though the call occurred when the 17-year-old Sousa Jr. would either have been en route or actually at the San Francisco Zoo with the brothers, Paul Dhaliwal told Carlos Sousa Sr. that he had not seen his son.

The brothers remain at San Francisco General Hospital recovering from severe bite and claw wounds. Their names were provided by hospital and law enforcement sources who spoke on condition of anonymity because the family had not yet given permission to release their names.

According to court records, the brothers have had run-ins with authorities before. They were arraigned Oct. 22 on suspicion of public drunkenness and resisting a police officer charges. They pleaded not guilty and are scheduled to be in court in January.

Paul Dhaliwal also has three other cases in Santa Clara County: an arrest for reckless driving and evading a police officer and being a minor in possession of alcohol and public intoxication, according to court documents.

On Thursday, more details of the tiger attack were revealed. The last minutes of Sousa Jr.’s life were spent trying to save his friend from the tiger that was mauling him at the San Francisco Zoo, only to have the animal turn on him, police and family members said.

Sousa Jr. and his friend's brother desperately tried to distract the 350-pound Siberian tiger, but the big cat instead came after Sousa.

"He didn't run. He tried to help his friend, and it was him who ended up getting it the worst," the Sousa Sr., said Thursday after meeting with police.

The heroic portrait of Sousa and a timeline of the dramatic Christmas Day attack emerged as officials revealed that the tiger's escape from its enclosure may have been aided by walls that were well below the height recommended by the accrediting agency for the nation's zoos.

San Francisco Zoo Director Manuel A. Mollinedo acknowledged that the wall around the animal's pen was just 121/2 feet high, after previously saying it was 18 feet. According to the Association of Zoos & Aquariums, the walls around a tiger exhibit should be at least 16.4 feet high.

Mollinedo said it was becoming increasingly clear the tiger leaped or climbed out, perhaps by grabbing onto a ledge. Investigators have ruled out the theory the tiger escaped through a door behind the exhibit at the zoo, which remained closed Friday.

"She had to have jumped," he said. "How she was able to jump that high is amazing to me."

Mollinedo said safety inspectors had examined the wall, built in 1940, and never raised any red flags about its size.

"When the AZA came out and inspected our zoo three years ago, they never noted that as a deficiency," he said. "Obviously now that something's happened, we're going to be revisiting the actual height."

The 4-year-old tiger, a female named Tatiana, went on a rampage near closing time Tuesday, killing Sousa and severely injuring the two others before police shot it to death.

After interviewing the brothers, police said Kulbir Dhaliwal was the animal's first victim.

As the tiger clawed and bit him, Sousa and the younger brother yelled in hopes of scaring it off him, police said. The cat then went for Sousa, slashing his neck as the brothers ran to a zoo cafe for help.

After killing the teenager, the tiger followed a trail of blood left by Kulbir Dhaliwal about 300 yards to the cafe, where it mauled both men, police said.

Four officers who had already discovered Sousa's body then arrived and found the cat sitting next to one of the bloodied brothers, police Chief Heather Fong said. The victim yelled, "Help me! Help me!" and the animal resumed its attack, Fong said.

The officers used their patrol car lights to distract the tiger, and it turned and began approaching them, leading all four to open fire, she said.

Police are still investigating how Tatiana was able to leave the enclosure.

Zoo officials said a "moat" separating the habitat from the public viewing area that measured 33 feet across contained no water, and has never had any. They did not address whether that affected the tiger's ability to get out.

At least one expert said the wall was low enough for the tiger to leap to the top.

"I think it could be feasible for a cat that has been taunted or angered," Jack Hanna, former director of the Columbus Zoo, said Thursday. "I don't think it would ever just do it to do it."

But another was more skeptical.

"It all depends on the surface and whether they could climb up it," John Seidensticker, head of the Conservation Ecology Center at the Smithsonian National Zoological Park, said. "I really don't think a tiger could spring that high. A leopard could. A leopard could in a minute."

Seidensticker emphasized that he has not seen the San Francisco Zoo's tiger enclosure.

Police have not addressed whether the victims had teased the tiger.

On Thursday, Fong denied earlier reports that a shoe and blood was found inside the enclosure. No shoe was found inside, but a shoe print was found on the railing of the fence surrounding the enclosure, and police are checking it against the shoes of the three victims, she said.

She also said there was nothing in their investigation so far that the boys "did or did not go over the railing" separating the public from the animal's enclosure.

AZA spokesman Steven Feldman said the minimum recommended height of 16.4 feet is just a guideline and that a zoo could still be deemed safe even if its wall were lower.

Accreditation standards require "that the barriers be adequate to keep the animals and people apart from each other," Feldman said. "Obviously something happened to cause that not to be the case in this incident."

Many other U.S. zoos have significantly higher walls around their tigers.

Mollinedo said surveillance cameras and new fencing will be installed around the exhibit.