Carlos 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 teen’s father, Carlos 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 12 1/2 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.

Brothers Paul Dhaliwal, 19, and Kulbir Dhaliwal, 23, were at San Francisco General Hospital with 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.

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.