05:25 PM CDT on Monday, July 17, 2006

Associated Press

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Mental illness led Andrea Yates to drown her five children in the bathtub, although she knew it was wrong, a forensic psychiatrist testified Monday.

“Did mental illness cause her to kill her children? It was one of the significant causes,” Dr. Park Dietz, testifying for the prosecution, told jurors in her second murder trial.

He said Yates suspected that Satan put thoughts of harming her children into her head, although she didn’t think he was ordering her to do so, based on what she told another psychiatrist and her letters to a pen pal.

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

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.

Dr. Michael Welner, a forensic psychiatrist who evaluated Yates in May, began his testimony on Monday.

After prosecutors rest their rebuttal case, defense attorneys will call their rebuttal witnesses. Closing arguments were expected later this week.

Dietz’s erroneous testimony about a television show in Yates’ first trial led an appeals court to overturn her 2002 murder conviction.

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.

The judge has barred attorneys from mentioning anything about that issue in this trial.

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

Her attorneys say she suffered from severe postpartum psychosis and did not know that drowning 6-month-old Mary, 2-year-old Luke, 3-year-old Paul, 5-year-old John and 7-year-old Noah was wrong.

But prosecutors say Yates’ actions belie those claims. The 42-year-old homemaker drowned the youngsters during the hour when she would be alone with them, after her husband went to work and before her mother-in-law arrived to help care for them. Then Yates called 911, and she later told a detective she killed them because she was a bad mother and wanted to be punished, according to testimony.