A man accused of killing his wife in Kansas had wanted to introduce another woman into their sexual life, leading his wife to begin a lesbian affair that he then blamed for the breakdown of their marriage, the deceased woman's divorce attorney told jurors Tuesday.

A defense attorney for James Kraig Kahler, who could face the death penalty if convicted, later dismissed that claim as "a fantasy."

Kahler, 48, is accused of fatally shooting 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 that his wife, Karen, had with another woman and 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. He was living near Topeka at the time of the killings.

Dan Pingelton, a Columbia, Mo., attorney who represented Karen Kahler in their divorce, testified that she told him that her husband introduced her to Sunny Reese of Weatherford, Texas.

James Kraig 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 during the criminal trial in Lyndon. "She indicated to me that Kraig wanted to do a threesome."

After the trail ended for the day, one of Kahler's lawyers said he'd never heard the claim before Tuesday's testimony.

"Mr. Kahler's accused of doing a number of things," Thomas Haney of Topeka said during an interview. "That's one that I think is just a fantasy."

The victims of the shootings were: Karen Kahler, 44; her grandmother, Dorothy Wight, 89, and the Kahlers' daughters, Emily, 18, and Lauren, 16. At the time of the killings, Kahler was living in Meriden, Kan., northeast of Topeka.

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 from The Associated Press. She is scheduled to testify Wednesday as a prosecution witness and has been subpoenaed as potential witness by defense attorneys.

During opening statements Monday, Haney said the Kahlers appeared to have a perfect marriage and family life for more than two decades before 2009, when the marriage became "cancerous."

He named Reese repeatedly as the cause and said the two women conducted their affair openly, in front of the Kahler children.

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.