Houston ? The fate of Andrea Yates hinges on whether the jurors who start hearing evidence today will believe she knew the difference between right and wrong when she drowned her five young children in their bathtub, then called 911 and told police what she had done.

The 37-year-old woman faces two capital murder charges in the June 20 deaths of three of her five children, ranging in age from 7 years to 6 months.

Defense attorneys say the former nurse turned stay-at-home mom is innocent by reason of insanity. They will try to prove that she suffered from a severe mental disease or defect that prevented her from knowing that holding her children beneath water until they could no longer breathe was wrong.

“We know that drowning children is wrong,” defense attorney George Parnham said during jury selection. “Objectively, we could all sit here and say those actions are wrong, but you’re going to be asked to view those actions through her eyes.”

Legal experts say he could face a difficult job during the trial, which is expected to last three weeks.

“When you have a crime like this that is so heinous, I think the jurors’ inclinations are likely going to be somewhat disinclined to find insanity,” Baylor University law professor Brian Serr said. “The fact that she called the police right afterward and reported herself in essence really undermines the fact that she thought what she was doing was right.”

Before jurors get to hear evidence about Yates mental state at the time of the drownings, they will hear the details of the case, including the 911 call Yates placed after she drowned the last child, Noah, 7, whose body was discovered face down in a bathtub half full of water.

They also will hear the confession Yates gave to police when they arrived at her door, how the officers found the youngest four children’s wet bodies on a bed covered with a sheet, and a taped interview that followed her arrest.

Prosecutors also will likely point to testimony from Yates’ competency hearing that she made the decision to drown her children the night before, and that after her husband left for work she drowned her children one at a time before her mother-in-law was to arrive.

Yates’ husband said she suffered from depression after the births of her two youngest children. Medical records detail her bouts with depression, and show that she attempted suicide twice after the birth of her fourth child in 1999 and was warned by a doctor to carefully consider whether she should have any more children.