Lyndon ? A Missouri man charged with the murder of his wife had told her he wanted to introduce another woman into their sexual life, leading her to begin a lesbian affair that he then blamed for the breakdown of their marriage, the deceased woman’s divorce attorney testified Tuesday.

Prosecutors are seeking the death penalty for James Kraig Kahler, 48, whom they accuse in the fatal shooting of his estranged wife, her grandmother and the Kahlers’ two teenage daughters. They were killed the weekend after Thanksgiving 2009 in the grandmother’s home near Burlingame, about 20 miles south of Topeka.

Kahler’s attorneys contend he had been mentally ill for months. They say he suffered hallucinations, and was obsessed with the relationship his wife, Karen, had with another woman as well as her pursuit of a divorce. The killings occurred only months after Kahler lost his job as a water department director in Columbia, Mo. — an event defense attorneys say was tied to his deteriorating mental health.

Dan Pingelton, a Columbia, Mo., attorney who represented Karen Kahler in their divorce, said she told him that her husband introduced her to Sunny Reese of Weatherford, Texas. Kahler and his attorneys say Reese broke up the marriage. The Kahlers lived in Weatherford before James Kraig Kahler, commonly known as Kraig, took the Missouri job in 2008.

“Karen indicated to me that Kraig wanted to bring another partner into the marriage,” Pingelton testified. “She indicated to me that Kraig wanted to do a threesome.”

The victims of the shootings were: Karen Kahler, 44; her grandmother, Dorothy Wight, 89, and the Kahlers’ daughters, Emily, 18, and Lauren, 16.

The Kahlers also had a son, Sean, now 12, who was at the scene of the shootings but fled without being physically injured. He testified Monday that he saw his father shoot his mother.

The boy told defense attorneys that he didn’t want to talk about his mother’s relationship with Reese, and they didn’t ask him to do so.

Kahler’s attorneys have put Reese at the center of his defense. She did not respond to phone messages or an email Tuesday. Reese is scheduled to testify Wednesday as a prosecution witness.

Thomas Haney, a Topeka attorney representing the defendant, told the court that the Kahlers appeared to have a perfect marriage and family life for more than two decades before 2009, when, he said, the marriage became “cancerous.”

He blamed Reese and said the two women conducted their affair openly.

Questioned by Haney, Pingelton acknowledged that he never interviewed Reese or the Kahlers’ children. Pingelton also said he did not know how Kraig Kahler introduced Reese to his wife, who worked with Reese as a personal trainer in Weatherford.

“She said the three of them were close, and then they broke away from Kraig,” Pingelton testified.

He also testified that money was an issue in the Kahlers’ divorce and that Kraig Kahler had contested “everything.”

A settlement hearing in the divorce had been scheduled for early December 2009, with a trial set just days before Christmas. Karen Kahler had filed for divorce in January 2009 and moved out of the family home in March.

“In a few months, it became fairly contentious, and it became worse as time went on,” he said.

In an interview with The Associated Press two days after the killings, Pingelton described Kraig Kahler as a controlling misogynist who was only interested in his son.

Questioned by Haney in court Tuesday, Pingelton acknowledged those statements, even calling the defendant “a monster.”

Haney, who has repeatedly described Kahler as a loving father and husband, suggested several times that Pingelton was speculating. Pingelton insisted his comments were “an informed opinion.”

At the time of the shootings, Kahler also faced a misdemeanor battery charge in Missouri, stemming from a March 2009 altercation with his estranged wife. According to evidence presented in the capital murder trial, Kahler tried to hug her when she did not want to be touched by him.

Pingelton testified that his file contained color photographs of Karen Kahler with bruises on her upper arms, and black-and-white copies were admitted as evidence Tuesday. But Pingelton testified he couldn’t say who took the photos or when.