He was allegedly furious that his wife had begin an affair with Sunny Reese after he had introduced the pair in the hope of kinky sex games.
Her divorce attorney Dan Pingelton testified: "She indicated to me that Kraig wanted to do a threesome."
But instead Karen and Susan had begun a relationship without him and armed with an automatic rifle, he went to Wight's home near Topeka, Kansas and took his horrific revenge on the whole family apart from his son Sean, now 12, who testified Monday that he saw his father shoot his mother.
Kahler's attorneys contend he had been mentally ill for months, saying he suffered hallucinations and was obsessed with the relationship between Karen and Susan and her pursuit of a divorce. According to KOAM, during opening statements Monday, his attorney Thomas 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.'