DENVER (AP) -- A Denver man accused of killing his wife while she was on the phone with a 911 dispatcher ate marijuana-infused candy before the attack, according to search warrants released Thursday. Denver police are investigating if the pot influenced his behavior and also whether officers responded quickly enough to pleas for help from the woman, who was shot to death 12 minutes into the 911 call she made Monday. Officials said Thursday that a dispatcher has been placed on paid leave during the investigation. Kristine Kirk, 44, told dispatchers her husband bought and ate the marijuana candy and may have also taken prescription pain pills before he started hallucinating and frightening the couple's three children, the warrants state. She pleaded with dispatchers to hurry and send officers because her husband, Richard Kirk, 47, had asked her to get a gun and shoot him. She said he was talking about the end of the world and she was "scared of what he might do." Richard Kirk could be heard in the background of the 911 call talking about the candy he legally bought from one of Denver's pot dispensaries earlier that night, and surveillance footage from the shop captured the transaction, police said. Detectives found a receipt for items such as "Karma Kandy Orange Ginger." A detective who interviewed Richard Kirk after the killing noted that he appeared to be on drugs, based on his speech and inability to focus, according to the warrants. Police said he was rambling and confessed to killing his wife. Investigators were analyzing blood samples to see whether he was under the influence of any other substances. Richard Kirk does not remember anything of the incident, his brother, Lance Kirk, told KUSA-TV Thursday. "He's hurting. He's hurting real bad," Lance Kirk said. Authorities have said Richard Kirk shot his wife in the head about 12 minutes into her call with 911, after she frantically told dispatchers her husband was getting a gun from a safe. Police Chief Robert White held a news conference Thursday but refused to provide details about the shooting or the internal investigation, nor would he say whether he thought officers took too long to respond. "This is an ongoing investigation, and I just cannot get into anything that would remotely compromise it," he said. "Obviously something went wrong because somebody lost their life." Officials have not released the 911 call or dispatch records publicly, but the search warrants offer new glimpses into Kristine Kirk's panicked final moments. Dispatchers could hear her telling her husband to stay down and yelling for her three young boys to go upstairs. "At one point she tells the 911 operator to 'please hurry' because he was scaring the kids and he was 'totally hallucinating,'" the documents say. Moments later, Kristine Kirk sounded "panicked" as she told dispatchers her husband was retrieving a gun from a safe. "She next related that he had the gun and she did not know where to go," the warrants say. Within a few seconds, dispatchers could hear her screaming. There was a single gunshot before the line went quiet. Officers arrived just after the shooting and found her dead of a gunshot wound to the head. The Denver Police Department has struggled with slowing response times in recent months as the number of officers has decreased due to retirements, departures and budget cuts that kept the department from hiring for five years. Disagreement exists about the reasons for the delays. The police union has said White's staffing changes and sweeping reorganization of the department have worsened the problem. White denied that claim Thursday and said he expects response times to improve as newly hired officers hit the streets.