COEUR d'ALENE — Shaun Kelly faces life in prison if convicted on charges stemming from allegations he forced the grandson of a former Post Falls mayor to eat a lethal dose of methamphetamine.

During an arraignment hearing Friday in Kootenai County District Court, Kelly, 43, pleaded not guilty to three felony charges — second-degree murder, unlawful possession of a firearm by a convicted felon, and aggravated assault — in connection to claims he pointed a gun at Evan Larkin, 22, and made him consume a fatal dose of methamphetamine to prove he was not a police informant. Kootenai County District Court Judge Cynthia Meyer also told Kelly prosecutors are seeking deadly weapon and persistent offender penalty enhancements in the case, which means Kelly could face an additional life sentence in prison if he is convicted.

On Aug. 20, 2015, Larkin was found unconscious in his truck, which was running but parked, in the valet parking area of the emergency room at Kootenai Health. Larkin never regained consciousness and died three days later, with the preliminary cause of death determined to be anoxic brain injury resulting from a methamphetamine overdose.

Larkin was the grandson of Clay Larkin, who served as the mayor of Post Falls for 13 years.

When police began investigating the death, multiple witnesses said they observed a man driving the truck into the hospital parking lot and exiting the vehicle, with Larkin still unconscious inside, before getting into a second car. Investigators were reportedly able to use surveillance footage at the hospital to identify the driver as Josh Brown.

Brown, according to court records, was interviewed by police shortly after, and told investigators he and Larkin had gone to a residence in Post Falls to meet someone named Shaun so they could "get high." Shaun, later identified as Kelly, allegedly made the two remove their clothes and took their phones and keys. Kelly later pointed what Brown reportedly described as an "M-16-style rifle" at Larkin and demanded Larkin eat a "1.8 gram rock of dope."

Initially, according to Brown, Larkin balked at the suggestion, but eventually ingested the drug. A short time later, Brown said Larkin began to "act strangely and overheat." The men, according to Brown, tried to cool Larkin off in the shower, but his condition did not improve.

According to the investigative report, Brown and Kelly carried Larkin to his truck, and Brown then drove Larkin to Kootenai Health.

Kelly was arrested in Spokane on July 1.

Kelly is being held at the Kootenai County jail on a $150,000 bond. A jury trial was tentatively scheduled in the case for Nov. 7.