Authorities investigate a homicide in Denver on April 15. (AP/The Denver Post/RJ Sangosti)

For 13 minutes, she told a 911 dispatcher her husband was hallucinating, talking about the end of the world and asking her to shoot him.

Then she realized he had gone to get his gun from a safe. She started screaming.

The sound of a gunshot ended the call.

By the time police got to the Denver home late Monday, Kristine Kirk, 44, had died from a gunshot wound to the head.

Police arrested Richard Kirk, 44, on suspicion of first-degree murder. He told them he killed his wife, according to a probable-cause statement. The Denver Post reported Kirk made his first court appearance Wednesday morning and will remain in custody without bail.

Now, police are digging deeper, trying to determine whether Kirk was using marijuana or another drug during the incident, authorities said Wednesday. A local Denver outlet said: “A source told FOX31 Denver that investigators are looking into the possibility Richard Kirk ate a marijuana edible before the shooting.”

Denver police spokesman Sonny Jackson told reporters that investigators are “looking at there possibly being a marijuana aspect to this particular investigation.”

It’s important to note that authorities have not confirmed a link between marijuana use and Monday’s incident involving the Kirk family.

If such a connection were proven, it would surely be seized on by opponents of legalized marijuana as Colorado became the first state to legalize the sale of recreational marijuana the first of this year.

Authorities have also been investigating the handling of the 13-minute 911 call, but declined to release the audio tapes, according to The Denver Post.

The Denver auditor’s office launched a study this year to examine police response times, the newspaper said, and a report is expected in June.

The department’s news release states:

“Any time a person dies while communicating with Denver’s emergency services, we examine the circumstances to ensure that the incident was handled properly and we look for areas to improve upon.”

The Denver Post reported that Chief Robert White said lengthening response times were due to fewer police officers and budget restrictions that have kept the city from hiring officers since 2008.