Jeffrey Serio found guilty of running over and killing man with his car
JACK UNDERHILL | Hagadone News Network | UPDATED 2 weeks, 3 days AGO
KALISPELL GOVERNMENT, HOUSING AND TRANSPORTATION REPORTER Jack Underhill covers Kalispell city government, housing and transportation for the Daily Inter Lake. His reporting focuses on how local policy decisions affect residents and the rapidly growing Flathead Valley. Underhill has reported on housing challenges, infrastructure issues and regional service providers across Montana. His work also includes accountability reporting on complex community issues and public institutions. Originally from Massachusetts, Underhill graduated from the University of Massachusetts, Amherst with a degree in Journalism before joining the Inter Lake. In his free time, Underhill enjoys mountain biking around the valley, skiing up on Big Mountain or exploring Glacier National Park. IMPACT: Jack’s work helps residents understand how growth, housing and infrastructure decisions affect the future of their community. | May 13, 2026 6:00 PM
A jury on Wednesday evening found suspected murderer Jeffrey Serio guilty of purposefully running over Maurice “Mory” Grigg with his car on an August evening last year.
The verdict was delivered after jurors deliberated the felony deliberate homicide charge for more than five hours. Serio sat hunched over, staring forward as the verdict was handed down.
The eight-day trial in Flathead County District Court in Kalispell began May 4 and featured testimony from witnesses, crime scene investigators and deputies who responded to the scene.
Judge Heidi Ulbricht placed the 48-year-old Serio into custody until his sentencing on June 26.
Serio was accused of killing Grigg by running him over with his Toyota Sequoia after allegedly snooping around Grigg’s property on foot and later driving the SUV erratically across his property and a nearby field.
Jurors heard closing arguments from prosecutors and Serio’s defense team on Wednesday. Deputy County Attorneys Amy Kenison and Ashley Frechette argued that Serio knowingly and purposefully killed Grigg, while defense attorney Alisha Rapkoch maintained that Serio was acting self-defense when he ran him over.
“This case comes down to self-defense and who is the first aggressor,” Frechette said.
Kenison told jurors that Serio chose to trespass several times on Grigg’s property off Birch Grove Road near Glacier Park International Airport.
“He had every opportunity to leave, but he didn’t,” Kenison said.
Serio allegedly crossed multiple fences on foot into Grigg’s backyard before Grigg guided him back to his car parked nearby. Serio allegedly came back again, prompting Sarah Born, who lives in a trailer on Grigg’s property, to dial 911.
A responding Flathead County Sheriff’s Office deputy told Serio to leave the property. After hopping in his car, Serio allegedly drove erratically through a nearby cornfield before busting through a pair of fences onto Grigg’s property, “using his car as a deadly weapon,” Kenison said.
Serio eventually crashed into a cell tower on the property, then allegedly reversed before witnesses reported hearing an engine revving, followed by a series of gunshots and another crash.
Serio allegedly left the vehicle on foot after running over Grigg and was later arrested by deputies. Grigg was found pinned beneath the vehicle and died at the scene. Investigators reported finding five shell casings at the scene that matched the firearm that Mory had on him. Two bullet holes were found in the front of Serio’s vehicle.
Defense attorney Rapkoch argued that Grigg put himself in danger by leaving the safety of his home, and that Serio ran him over in a split-second reaction to being shot at because he feared for his life.
“This is about choices on both ends here,” Rapkoch said.
Prosecutors countered that Serio dangerously swerving around the property had already posed a threat to Grigg and everyone else on the scene.
“He was not only a threat to Mory, he was a threat to everyone,” Kenison said. “The state submits to you, that that defendant is the original aggressor.”
Reporter Jack Underhill can be reached at 406-758-4407 or [email protected]. If you value local journalism, pledge your support at dailyinterlake.com/support.
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