Sign up for the Word on the Tree newsletter


Richard Kirk was sentenced to 30 years in prison in the shooting death of his wife on Friday. The 50-year-old father of three pleaded guilty to second-degree murder in an agreement with prosecutors. He had initially been charged with first-degree murder.

In April 2014, Kristine Kirk called 911 and reportedly said her husband was hallucinating — talking about the end of the world and asking her to shoot him. She was on the phone with an emergency operator for 12 minutes before the sound of a gunshot was heard on the line. Several minutes later, law enforcement officers found her lying dead with a gunshot wound.

Kirk originally pleaded not guilty to first-degree murder, before changing his plea to not guilty by reason of insanity. He has maintained that a marijuana-infused edible caused his behavior.

Prosecutor Helen Morgan said that Kirk’s cannabis use was one of the factors in the plea agreement. “There were a myriad of factors that went into it, but [marijuana use] was certainly one of them,” she told the Associated Press.

One of Kirk’s public defenders said they had a “groundbreaking defense” prepared to show that his marijuana use led to the shooting. “They had an emergency room doctor and other experts ready to testify, but Kirk ultimately agreed that his sons needed to avoid a trial,” reports The Denver Post.

The case has raised questions about the regulations within the cannabis industry. In 2016, Kirk’s children sued Gaia’s Garden LLC, the maker of the infused candy that was found in his home after the shooting. The lawsuit, filed by Kristine’s parents, alleged the company failed to include warnings about the edible’s possible side effects of hallucinations, paranoia, and psychosis. An attorney for the company said it followed state regulations on labeling.

While scientific evidence has suggested a link between cannabis use and schizophrenia, the nature of that link is still murky. Research shows that those with a genetic predisposition to developing the mental illness may also have a predisposition to smoking weed.

“There are detailed studies which have demonstrated that cannabis can have very different effects on the brain of someone who is at risk for schizophrenia than someone who isn’t,” cell biologist Matthew Hill told The Verge. Some studies suggest that those at risk for schizophrenia are more likely to experience adverse effects from cannabis use.

Kirk’s defense attorneys argued that he did not know he was at a high risk for psychosis due to a family history of schizophrenia. Prosecutors emphasized the couple’s escalating financial and marital troubles. Kristine had reportedly told a friend that she was afraid of her husband due to all the fighting in their marriage, though Kirk’s attorneys disputed the claim. Investigators said Kirk stood to gain from Kristine’s $340,000 life insurance policy.

“I did not know [the edible] would affect me the way it did… I know with certainty if I did not ingest that marijuana edible, Kris would still be here today,” Kirk told the judge.

Crimes like Kirk’s make national headlines in part due to the marijuana link: debate about cannabis policy reform is increasing across the nation as legalization spreads. However, cannabis use as a factor in violent crime is relatively rare. The National Crime Victimization Survey has consistently found that alcohol is more likely to be a factor in violent crime than any other drug. Alcohol is a factor in about 40 percent of violent crime, and that figure rises to 65 percent in spousal violence cases. (This is compared to 5 percent for all other drugs combined.)

Other studies of state-legal marijuana have found an association between legalization and declines in violent crime. Denver saw a 2.2 percent drop in violent crime rates after one year of legal pot sales. An analysis of state panel data found that medical marijuana legalization was associated with a drop in rates of homicides and assaults.

While prohibitionists will no doubt point to cases like Kirk’s as an argument against reforming marijuana policy, available data show that alcohol is really the worrisome drug when it comes to violence.

Sign up for Word on the Tree's daily email newsletter

The Word on the Tree newsletter is widely hailed by cannabis professionals, advocates, and journalists as indispensable reading. Get updates on policy reform, business dealings, and scientific research – all in a concise digest.