A Denver man accused of killing his wife after eating marijuana-infused candy he bought at a legal pot shop has pleaded not guilty to first-degree murder.

Richard Kirk, 48, entered his plea during a brief court appearance Friday as members of his family watched. He is charged with shooting Kristine Kirk, 44, last April while she was on a 911 call with police dispatchers.

The shooting stoked concerns about the effects of the marijuana snacks, which have become popular since the state legalized recreational pot shops. 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. Colorado now has stricter potency limits on edibles.

Defense attorneys have suggested that Kirk was so impaired by the "Karma Kandy Orange Ginger" that he may not have intended to kill his wife. She told dispatchers that he was acting more drunk than violent, crawling through a bedroom window and cutting his legs on broken glass.