Woroniecki's street preachings included the idea that women must be obedient to men and were responsible for their children's eternal salvation or damnation.
"I didn't want my kids to go to hell," said Yates.
In the months leading up to the murders, Yates' mental health deteriorated and she was hospitalized twice after the birth of Mary and the death of her father. When she returned home, she felt her children becoming more distant and withdrawn.
Yates became convinced that she was a bad mother, influenced by Satan. She felt pressured to kill her children while they were still pure.
"She believed that if she had waited longer, that they would be so corrupted by Satan that God would no longer allow them to heaven and they'd go to hell," said Puryear. "But in their innocence, while they were still so young, that God would take them."
Sixteen days before the drownings, her doctor made what some believe was a critical mistake: He took her off Haldol, a powerful anti-psychotic drug.
As the voices inside her head grew louder, she says she was afraid to ask for help.
"Satan can't read your thoughts, but if you say 'em aloud, he, he will hear them and he'll use 'em against you," Yates said. "I thought if I verbalize these fears that they would come about."
Less than a year after the drownings, defense attorney George Parnham represented Yates at her death penalty trial when the jury found her guilty.
"She knew she was going to hell, and she did the ultimate act of love, and sacrificed herself and saved her kids," Parnham said.
Yates was sentenced to life in prison in 2002, but that conviction was overturned and in her second trial, which ended July 26, things went differently.
"Five years ago, we couldn't get a jury past the pajamas and the crime scene videos. Very, very difficult to understand, to accept," Parnham said.
A lot had changed since 2001, including ideas about mental illness, and some of those changes were fueled in part by what Yates had done. But could the jury get past the horror of the crime?
Now, five years after she killed her kids, Yates has undergone a significant amount of medication and therapy. She can now talk about the details of that morning.
Yates said she waited until her husband left to start filling the tub. She said, "Drowning them" is "all I thought about."
Yates had a small window of opportunity -- one hour -- between the time her husband left the house and when her mother-in-law, Dora Yates, was expected to arrive. Doctors had warned the Yates family that Andrea Yates was not supposed to be left alone with the kids.
Welner says his videotaped interview showed that Yates had planned the murders for a long time but waited for the right moment when she knew there was no one around.
Here are some excerpts from Welner's conversation with Yates, from the tapes obtained by ABC News:
Welner: "Was Satan driving you to do this at the time? Did you think, at the time, that you were doing this because Satan was compelling you to do it? And, you know, the answer is the truth. The answer isn't the right answer. Just tell me the truth."
Yates: "Yes. I felt that."
Welner: "OK. This is why I'm uncomfortable with that answer. This is what you have to make sense from. If ... if Satan was driving you to do this, either Satan was driving you to do this, or you did this because you wanted your kids to go to heaven."