Andrea Yates' defense attorneys will call their final rebuttal witnesses as her capital murder trial in the drownings of three of her five children enters its fourth week.

Over the weekend, prosecutors rested their case against Yates, 37. Testimony was to resume Monday morning.

Whether Yates knew her actions were wrong as she drowned her five children in the bathtub last summer will be the main issue jurors have to decide when deliberations begin.

Neither the state nor the defense is contesting that Yates suffered from a severe mental disease or that she killed her five children June 20.

To prove insanity, defense attorneys must show by a preponderance — or greater weight — of the evidence that Yates suffered from a severe mental disease or defect that prevented her from knowing her actions were wrong.

In Texas, a person is presumed sane.

Psychiatrists called as expert witnesses during the trial, which began Feb. 18, by prosecutors and defense attorneys have said Yates suffered from schizophrenia, a severe mental disease. What the witnesses disagreed on is whether Yates could appreciate the wrongfulness of killing her children.

Dr. Phillip Resnick, called by the defense, said Yates knew her actions were illegal but that in her psychotic delusional state, she believed them to be right.

Resnick told the eight-woman, four-man jury that Yates believed Satan lived within her and that she could save her children from eternal damnation only by killing them.

Another defense witness, Dr. Lucy Puryear, who specializes in women's mental health and reproductive issues, said Yates had no idea her actions were illegal.

Puryear testified that Yates' mind was fogged by psychosis for months after the drownings and likely for months beforehand.

But Dr. Park Dietz, hired by the state, says Yates' psychosis and mental illness did not keep her from carrying out or making plans.

Dietz told jurors that Yates knew her actions were wrong in the eyes of the law, society and God. He said Yates didn't mention Satan until the day after her arrest and said she likely slid downward after her arrest when she realized she had killed her five children and found herself naked in a jail cell on suicide watch.

Another state expert, Dr. Harry Wilson, described Yates as deliberate and determined as she drowned her children. Wilson, who specializes in pediatric pathology, said all of Yates' children struggled for their lives. He said Yates removed the bath mat from the tub to deter their struggles.

Yates faces life in prison or the death penalty if convicted in the drownings of 7-year-old Noah, 5-year-old John and 6-month-old Mary. Charges later could be filed in the deaths of Paul, 3, and Luke, 2.

If jurors decide she was insane at the time of the killings, the court will have to wait at least 30 days before deciding whether she should be committed to a mental hospital or go free.