HOUSTON (AP) — Before she drowned her children, Andrea Yates removed the mat inside the bathtub, turned on the water and put up the dog -- behavior that indicated she didn't want anything to get in the way of what she was about to do, a forensic psychiatrist told jurors.

She also deceived her husband so he would not suspect her plans, said Dr. Michael Welner, who evaluated Yates for two days in May.

"Her behavior demonstrates self-discipline, self-control and efficiency in carrying out the drownings of her five children," Welner told jurors Monday, testifying for the prosecution in its rebuttal phase in Yates' second murder trial.

Welner was to continue testifying Tuesday. Yates is being retried because her 2002 capital murder conviction was overturned by an appeals court that said some erroneous testimony may have influenced jurors.

Yates, charged in three of the children's deaths, will be sentenced to life in prison if convicted. She has again pleaded innocent by reason of insanity.

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Her attorneys say she suffered from severe postpartum psychosis and meets Texas' definition of insanity: that someone, because of a severe mental illness, does not know while committing a crime that it is wrong.

But Welner said he found 60 examples in his examination of how Yates knew drowning 6-month-old Mary, 2-year-old Luke, 3-year-old Paul, 5-year-old John and 7-year-old Noah was wrong. She filled the tub after her husband left, he said, and removed the bath mat so that the youngsters would have no traction to try and escape.

In an excerpt of Welner's videotaped interview with Yates played for jurors, he asked why she had been more determined on that day, June 20, 2001.

"I had made up my mind that I would to it. I just thought it had to be done," she said, adding that it was because of "just the prospect of them growing up to be unrighteous."

When Welner asked what made that day different from other days, she finally answered after a long pause, "I had just -- I didn't want them to go to hell."

Earlier Monday, another forensic psychiatrist who evaluated Yates more than four months after the killings finished his third day of testifying. Dr. Park Dietz's erroneous testimony about a television show in Yates' first trial led an appeals court to overturn her 2002 murder conviction last year.

Dietz, also a consultant to "Law & Order," said the series had aired an episode about a woman who was acquitted by reason of insanity after drowning her children. After Yates' conviction, but before she was sentenced to life in prison, those involved in the case discovered no such episode existed.

He said he "may have spoken inartfully in the past" about her psychosis but that he believes Yates suffered from depression since 1999 and had some psychotic symptoms, such as when she believed surveillance cameras were in her house and when she thought cartoon characters were speaking to her through the television.

He acknowledged that he testified in her 2002 trial that she was psychotic the day of the drownings and for two years before that.

"Did mental illness cause her to kill her children? It was one of the significant causes," Dietz said Monday.