PHOENIX (AP) -- Scott Falater doesn't deny stabbing his wife 44 times.
He doesn't deny holding her head under water in their swimming pool as the life bled out of her.He doesn't deny stashing the knife and his bloody clothes in his Volvo before police arrived.
But he does deny being able to remember anything about it. Falater's defense to first-degree murder charges: He was sleepwalking.
"He did it without any conscious thought. He did it because he was sleeping," defense lawyer Michael Kimerer told jurors at the start of Falater's trial. The defense is seeking acquittal.
The defense portion of the case continues Monday, with psychologist Janet Tatman facing cross-examination by prosecutors. She says sleepwalking is the best explanation for Falater's actions.
Prosecutor Juan Martinez says the sleepwalking claim is nonsense, and he plans to seek the death penalty if Falater is convicted. Martinez told jurors that Falater's actions were too deliberate to have been the work of a sleepwalker.
Two years ago, on a night in January, neighbors heard Yarmila Falater's screams and moans for up to 30 minutes.
Greg Koons has testified he watched over his back-yard fence as Falater went inside to wash his hands, ordered his dog to lie down, then rolled his wife's body into the pool and held her head under water.
Kimerer and Falater's family describe him as a mild-mannered family man, a devoted husband and father.
"He couldn't kill anybody," said his father, Fred Falater.
But Martinez has said there were problems in the Falaters' marriage and has a request pending to allow a witness to testify that, in the months before her death, Yarmila Falater said she once caught a sexually transmitted disease from her husband.
Sleep disorder experts say it is possible for people to perform complex tasks -- and even kill -- while sleepwalking.