Defense argues self-defense as Jeffrey Serio's homicide trial opens in Flathead County District Court
JACK UNDERHILL | Hagadone News Network | UPDATED 2 days, 18 hours 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 6, 2026 12:00 AM
Suspected murderer Jeffrey Serio’s attorney argued Tuesday that the 48-year-old acted in self-defense when he fatally ran over Maurice “Mory” Grigg with his car on an August evening last year.
That was one of the explanations jurors heard during opening statements in Serio’s deliberate homicide trial in Flathead County District Court on May 5. Judge Heidi Ulbricht is presiding over the trial, which began Monday and is expected to run through May 12.
“The evidence will show that Jeff Serio lived through seconds of absolute fear,” said defense attorney Alisha Rapkoch. “This case is about a tragedy and self-defense.”
But Deputy County Attorney Ashley Frechette, who is prosecuting the case alongside Deputy County Attorney Amy Kenison, told jurors that Serio trespassed several times before knowingly killing Grigg. The fatal collision occurred on Grigg’s property off Birch Grove Road near Glacier Park International Airport.
“Mory’s last day alive, at his home, where he was having family and friends over for pizza. A pizza party that ended with the defendant running down Mory with his vehicle, dragging him over 40 feet, through a power box, through a fence and into a field,” she told jurors.
Serio first parked his white Toyota Sequoia on a dirt road at a neighboring property before walking onto Grigg’s land, Frechette said. After Serio crossed several fences into Grigg’s backyard, Grigg helped him back over the fence so he could return to his car, Frechette said.
But Serio allegedly returned, prompting Sarah Born, who lives on Grigg’s property in a trailer, to dial 911. Authorities first received a call at 7:38 p.m., according to charging documents.
A responding Flathead County Sheriff’s deputy told Serio to leave the property.
Serio eventually made his way back to his car and started driving erratically through a nearby sunflower field and cornfield before speeding onto Grigg’s property.
Grigg allegedly chased after the car as Serio crashed into a cellular tower. The collision was followed by gunshots and a second crash. Investigators reported finding five shell casings at the scene, with two bullet holes in front of Serio’s vehicle.
Rapkoch argued that Serio unintentionally ran over Grigg in the heat of the moment while trying to avoid gunfire from Grigg. Frechette maintained that Serio acted intentionally.
While jurors will be able to hear gunshots and a crash in video evidence, “you won’t see a direct line of sight to the scene of the murder,” Frechette said.
“The only two people who truly know what happened in those obscure moments were Mory and Jeff. And one of them is dead,” Rapkoch said. “But the other one is sitting here, about to trust all of you. And Jeff will tell you what happened that day.”
Serio allegedly left the vehicle on foot after running over Grigg and was later arrested by deputies. Grigg was found pinned beneath the vehicle. Deputies employed jacks to free him, but he died at the scene, officials said.
PROSECUTORS AND Serio’s defense team began clashing almost immediately as the trial began. Frechette objected after Rapkoch told jurors during her opening statement that the responding deputy determined Serio was not intoxicated during their initial encounter.
Ulbricht ruled that intoxication could only be considered until after Serio testified.
Frechette also objected when Rapkoch said Grigg’s sister will testify that the responding deputy told Grigg to fire warning shots if Serio came back on the property, describing it as hearsay.
Throughout the week, jurors are expected to hear from guests at Grigg’s pizza party, deputies that responded to the scene, investigators that examined Grigg’s injuries and the bullet holes found in Serio’s car, and watch video footage taken by Brown.
Serio remains in custody in the county jail on $500,000 bail.
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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