PHOENIX, Ariz. (Court TV) — Scott Falater is expected to take the stand Wednesday and try to convince jurors that he did not purposely kill his wife during a sleepwalking episode.

Falater is on trial for allegedly murdering Yarmila, his wife of 20 years, on January 16, 1997. Falater stabbed his wife 44 times at their home, dragged her into their pool and then held her head under water.

Falater claims he does not remember anything from the attack. He insists he did not plan his wife's death. During the three-week trial, the defense has portrayed Falater as a mild-mannered and loving husband who would never have committed such a heinous crime had he been fully cognizant.

Falater may have to humanize himself and convince jurors that he loved his wife, who was his high school sweetheart and had no reason to kill her. He also must convince them that he is truly sorry for his actions. Falater's children, Megan and Michael, have testified that their parents had a loving marriage.

But prosecutor Juan Martinez is expected to try to dismantle Falater's defense by suggesting that the marriage was not as harmonious as the defense would like jurors to believe. Reportedly, Martinez plans to use several rebuttal witnesses who may testify that there were several signs of strain in the Falater marriage.

Martinez may also ask Falater about his history of sleepwalking. Both his parents and his sister have told jurors about his past sleepwalking spells, most of which were apparently caused by stress. This may give Martinez an opportunity to ask Falater about any stress he may have felt from either his job as a Motorola engineer or due to family pressures present at the time of his wife's death.

Falater may also have to answer allegations that he discussed a similar sleepwalking murder case with a colleague weeks before his wife's death. In that 1987 case, a Canadian jury acquitted the defendant of murder.

On Tuesday, Rosalind Cartwright, a defense psychologist who is the head of a sleep disorder center in Chicago, refuted prosecution suggestions that Falater faked his sleepwalking episode on the night of his wife's slaying. Cartwright, who said she has studied hundreds of cases involving sleepwalking violence, said Falater's was "the purest case I've seen with an act of violence of this kind."

Although Martinez noted that she wrote in a pre-examination report that she thought Falater suffered from a sleep disorder, Cartwright insisted that she did not reach her conclusions too quickly. She said Falater was not malingering, and she was not conned.

If convicted of murder, Falater could face the death penalty.