Dr. Park Dietz is on the stand again today for a third day of testimony and cross-examination in the Andrea Yates retrial. On Friday, he gave his reasons why he thinks Yates does not meet the statutory requirements for legal insanity.
Park Dietz, a forensic psychiatrist, said Yates quoted Scripture to him when she talked about the killings.
"My children weren't righteous," she said. "They were going to stumble. Better for them to tie a millstone around their necks and they should perish than they should stumble."
Dietz, whose erroneous testimony four years ago resulted in Yates' new trial, said the former Clear Lake-area housewife's religious beliefs indicate she knew the killings were wrong. She considered killing them a sin and believed her homicidal thoughts came from Satan, Dietz said.
"Mrs. Yates, in assessing her obsession to harm the children, regarded that idea of harming the children was a sin," Dietz said. "That killing the children would be sinful is an indication that it would be wrong from her point of view."
[Defense attorney George] Parnham also asked Dietz about his testimony in the 2004 capital murder trial of Deanna Laney, who was acquitted by reason of insanity.
In Laney's trial, Dietz said that psychotic delusions made Laney unable to determine right from wrong during the killings - the legal standard in Texas' legal standard for insanity.
Laney, who believed God chose her and Yates as witnesses after the end of the world, said she believed God had told her to kill her three children.
Dietz testified that Laney believed she was right to kill her children because God would never order her to do wrong.
Parnham asked Dietz if people commanded by God to kill are insane.
"Only if a person is of a faith that believes God is good and infallible."
He said Yates told him in a interview in November 2001 that Satan was the origin of thoughts about harming her children.
"Because Mrs. Yates said that the thoughts were bad, she knew it was wrong, and because of her faith she concluded they were from Satan," Dietz said.
"We go back to the word 'know,'" Parnham says. "Does 'know' mean a perception on the part of the sick person that society would view her actions as being illegal or wrong, but she knows them to be right? The danger is that what we do with our (Texas) standard is impose our own logic - our own logic that is unfettered by mental disease. If you're psychotic, you live in a different real world."