Six days after bashing her sons' heads with rocks, Deanna Laney (search) calmly recounted the killings and told a psychiatrist she was awaiting her children's resurrection, according to a videotape shown to the jury Thursday.

Laney's behavior was in chilling contrast to the sobbing, emotionally broken and seemingly tortured demeanor she displayed in a video made seven months after the attacks, and shown to jurors Wednesday.

In an interview videotaped days after Laney killed her two older sons and severely injured her toddler, she was wide-eyed, occasionally smiling and animated as she described events leading up to the bloodshed last Mother's Day (search) weekend.

The tape was played as defense attorneys began their case in the trial, which began Monday.

"I feel like that I obeyed God and I believe there will be good out of this," she told psychiatrist Dr. Phillip Resnick. "I feel like he will reveal his power and they will be raised up. They will become alive again."

Laney, 39, has pleaded innocent by reason of insanity to charges of murdering 8-year-old Joshua and 6-year-old Luke and severely beating Aaron, then 14 months old.

Resnick testified Laney was suffering from psychotic delusions and was incapable of knowing right from wrong at the time of the killings, the legal standard in Texas for insanity.

"She's separated psychologically from all the horror of it and she's simply a woman on a divine mission carrying out the Lord's will," he said. He said the delusions began weeks before the killings.

After she was jailed -- and before she took anti-psychotic medication -- she drank water from the floor and out of a toilet bowl because she felt she had not carried out God's orders perfectly, Resnick said. She was not sure she should have beaten Aaron, he said.

In court, Laney's husband, Keith Laney (search), held his head in his hands and appeared to weep after watching his wife's calm description of the violence.

Deanna Laney's sister, Pam Sepmoree, told jurors Thursday that her younger sibling had been a devoted mother. "The boys were her life," she said.

But before the slayings, she noticed her sister was eating less, losing weight and reading the Bible more. "She was low, she was down. She didn't talk much," Sepmoree said, explaining that she believed her sister was "very sick and insane" to have killed the boys.

Prosecutors have portrayed the slayings as selfish acts, and maintained Laney had to have known she was doing wrong. Her first call was to 911 to summon authorities.