DENVER – A Denver man accused of eating marijuana-infused candy he bought at a legal pot shop and then killing his wife while she described her husband’s erratic behavior on a 911 call has changed his plea to not guilty by reason of insanity.

Richard Kirk, 49, is charged with first-degree murder in the shooting death of his wife, Kristine, 44, in April 2014.

Defense attorneys have suggested that Kirk was so impaired by “Karma Kandy Orange Ginger” that he may not have intended to kill her.

The shooting stoked concerns about the effects of the marijuana snacks, which have become popular since the state legalized recreational marijuana stores.

Colorado lawmakers last year tightened regulations on edible marijuana, responding to the Kirk case and the death of a college student who jumped from a hotel balcony after eating a potent marijuana cookie.

Just before she was shot, Kristine Kirk told dispatchers that her husband was acting more drunk than violent, crawling through a bedroom window and cutting his legs on broken glass. But prosecutors argue he had the wherewithal to remember the code to a locked gun safe and press the weapon to his wife’s head.

Kirk pleaded not guilty in March. He has since gotten a new attorney, who did not respond to questions about the plea change.

It was unclear what role marijuana would play in his defense.

Kirk will be evaluated at the Colorado Mental Health Institute in Pueblo before a hearing scheduled for Dec. 19.

The couple had three young sons, who were home at the time of the killing.

On the 911 call, Kristine Kirk said her husband was paranoid and hallucinating after eating pot candy he bought at a recreational pot shop. Dispatchers heard the woman beg her husband not to retrieve a gun from a safe. Then they heard a gunshot and the line went quiet.

Colorado now has stricter potency limits on edibles. By next year, the state is expected to require each edible to be stamped “THC,” for the drug’s psychoactive ingredient.

Denver police Detective Troy Bisgard testified during Kirk’s preliminary hearing last year that the only substance found in Kirk’s blood was THC, marijuana’s intoxicating chemical, but drew no conclusions about whether the drug influenced his behavior. The detective said Kirk’s THC levels were relatively low.

The couple’s marital and financial problems were escalating, and Kristine Kirk was covered by a $340,000 life insurance policy, Bisgard said.

She had recently told friends she had grown afraid of her husband because they had been fighting so much.