Branch Davidian children's drawings foretold deadly Waco fire, psychiatrist says What the children who were raised inside the religious sect said during siege.

 -- Before the 1993 siege at Waco, Texas, ended in a horrific fire, a group of Branch Davidian children provided startling insight into the structure and motivations of the apocalyptic religious sect led by David Koresh.

The standoff began on Feb. 28, 1993, when 76 agents from the Bureau of Alcohol, Tobacco and Firearms arrived at the Mount Carmel Center compound with a search warrant to look for illegal weapons. A shootout between federal agents and Branch Davidians ensued, killing four ATF agents and six Davidians.

Watch "Truth and Lies: Waco," the documentary event, on Thursday, Jan. 4 at 9 p.m. ET on ABC

In the early days of the standoff, almost two dozen children were released into the care of the Methodist Children’s Home in Waco, where they were cared for by a team of trauma specialists.

“They had a pervasive belief that David Koresh was God,” chief psychiatrist Dr. Bruce Perry, who worked with 19 of the Davidian children, told ABC News.

“David was not to be questioned,” Perry said, adding that two adolescent girls in the group had already been selected by Koresh to join his harem of wives. “A set of young girls had been designated to become his brides. And they were disappointed this wasn't going to happen.”

According to former Davidians, Koresh could pick and choose among the women inside Mt. Carmel -- even the married ones.

“It’s sick and it’s perverted and yeah, it’s one of the things about David Koresh that probably bothers me the most,” former Davidian David Bunds, who was in his mid-20s at the time, told ABC News. “My position now is that David Koresh was a pedophile. I wish I would have done something. I don’t know what I would have done but I wish I had done something.”

Kiri Jewell, who told ABC News in a 2003 interview that her mother Sherri was one of Koresh’s wives, said she herself became Koresh's youngest "bride" when she was just 10 years old, and later testified before Congress that Koresh molested her at a motel. By Jewell’s account, Koresh had as many as 20 wives by the time he died on April 19, 1993.

While Perry doesn't believe any of the children under his care were physically sexually abused by Koresh, but he did say they received other forms of sexual abuse. “They all were exposed to inappropriate sexualized content, language and behaviors,” he said.

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Perry described first walking into a room to meet the children. “One of the littlest kids looked up at me and said, ‘Oh, are you here to kill us?’” Perry said the children were frightened, with resting heart rates twice as high as expected for a normal child.

Former Davidian Joann Vaega, who was 6 years old at the time, was one of the children released early in the standoff. Once on the outside, she told ABC News, “Everything was different.”

“Trying to understand what it’s like to take a bath just seemed very scary to me, flushing toilets scared the bejeebers out of me,” Vaega said. “I had no idea what the heck a basketball was.”

Margarida Vaega, Joann Vaega’s mother, would later perish in the fire on April 19. Joann Vaega has only one possession to remember her mother by. “She gave me her necklace,” said Vaega. “It really is the only thing she had.”

“While we watched them, we learned a lot about the belief system of the Davidians,” Perry said. “One of the things that all of these kids had learned to do, even the really young kids, was march and handle a gun.”

Perry said he also observed startling behavior foreshadowing the events of April 19. He said the children sang apocalyptic songs and drew "end of days"-type imagery.

“Younger kids would draw a picture of the compound with fire coming out of it and I’d say, ‘What’s that?’ and they’d say, ‘That’s none of your business. You’ll find out,'” Perry said.

“It was clear that there was this permeating apocalyptic perspective,” said Perry, adding that he passed along this information to the FBI and told the agency “that they really needed to be very cautious.”

On day 51 of the siege, the FBI launched an operation to remove the Davidians from their compound using tanks equipped with non-lethal tear gas. Officials said the Davidians responded by setting their home ablaze. Only nine survived the deadly fire, all others were killed -- approximately 80 in total, including around 32 women and 21 children. It was the deadliest standoff in U.S. law enforcement history.

“I have to say, I was horrified by what happened,” Perry said. “But I wasn't surprised.”

Watch "Truth and Lies: Waco," the documentary event, on Thursday, Jan. 4 at 9 p.m. ET on ABC