Houston ? Andrea Yates had a history of suicide attempts and was so psychotic that her delusions drove her to drown her children in their bathtub, Yates’ attorney told jurors Monday as her capital murder trial got under way.

Yates suffered from postpartum depression with psychotic features, “the cruelest and most severe of mental illnesses,” defense attorney George Parnham said.

Andrea Yates

Prosecutors seeking the death penalty for Andrea Yates agreed she suffered from a mental illness but contended she was well aware her actions were wrong when she held each of her children beneath water until they could no longer breathe.

“She knew this was an illegal thing,” Harris County assistant district attorney Joe Owmby said during opening statements. “It was a sin. She knew it was wrong.”

Yates, 37, fidgeted and pulled at her fingers as she sat at the defense table. She is charged with two counts of capital murder for the June 20 drownings of three of her five children, ages 6 months to 7 years. She has pleaded innocent by reason of insanity.

She could wind up in a mental institution, prison or on death row.

Parnham said the evidence during the expected three-week trial will show that psychosis so clouded Yates’ mind that she didn’t know what she was doing, let alone that it was wrong.

Owmby said there were many signs that Yates knew what she was doing was wrong. Owmby said Yates told police that she should go to hell for what she had done and that she waited to drown the children until her husband, Russell, left for work because he would have stopped her.

“Andrea Yates had a mental illness,” Owmby said. “She also called the police after she killed these children.”

Jurors heard Yates’ 911 call Monday as testimony began. She requested police and an ambulance and told the dispatcher she was “ill,” but did not elaborate. When dispatcher Dorene Stubblefield asked if she was alone, Yates said, “No, my kids are here.”

During the call, Yates paused frequently and breathed heavily.

Owmby said police arrived at the home to find four of the children’s bodies on a bed under a sheet. Six-month-old Mary’s head was cradled in 5-year-old John’s arm. Noah, 7, was floating face down in the bathtub with his arms outstretched.

“The breath was taken out of their bodies by the defendant, Andrea Pia Yates,” he said.

If Yates is found innocent, a hearing will be at least 30 days later where she will either be released or involuntarily committed.