Within minutes of the Friday stop, both were dead, dividing this town's 924 residents between those who see McKay as a fallen hero and those who considered him a bully with a badge.
"It's a tragic situation — two men lost and two families devastated," said Steve Heath, owner of the Franconia Village Store.
Beyond that, there's little agreement about the tragedy in Franconia, where local Olympian Bode Miller — Kenney's cousin — is royalty. His image appears on posters, signs and keepsakes all over town.
Authorities say McKay, 48, stopped Kenney, 24, for speeding, and Kenney asked to deal with a different officer and drove away.
By the time McKay caught up about a mile down the road, Kenney was in a frenzy, according to his friend and passenger, Caleb Macauley.
"I've never seen anyone so scared in my life," Macauley told WMUR-TV.
McKay forced him off the road and pepper-sprayed him. Kenney then shot McKay four times and drove over him.
Gregory Floyd, a passing motorist and ex-Marine who saw it all, grabbed McKay's gun and shot Kenney to death when he refused to put his gun down. Authorities quickly ruled the killing justified.
McKay, who had a 9-year-old daughter, was to have been married in July atop Cannon Mountain, where Bode Miller learned to ski. Instead his funeral will be held at the mountain.
As many as 6,000 officers from throughout the country are expected to attend Thursday's funeral, but in this close-knit mountain valley, where the Kenney family's roots run deep, at least one town may hold back.
Plans to send two fire department vehicles from neighboring Easton triggered a heated debate at the selectmen's meeting Monday night. Chairman Paul White, who is married to Kenney's cousin, moved to keep them away in protest.
Liko Kenney grew up on his grandparents' rustic tennis camp in Easton, where the extended family still lives. Liko's parents own a coffee plantation in Hawaii, and he followed their seasonal migrations: the islands in winter, the White Mountains in summer.
"He was kinda just a happy, hippie kid. He'd do anything to help anyone," said Holly Hayward, 48, who said she'd known Kenney his whole life.
Friends and family called Kenney a free-spirited outdoorsman who loved all-terrain vehicles and had issues with authority. Court records show he could be volatile even with his own family. In January 2003, an aunt, Larisa Kenney, sought a restraining order against her nephew, then 19. In a handwritten letter, she told the court Liko had frightened her by chain-sawing trees near her cabin, sending one crashing onto her roof as she slept. When she confronted him, she said Liko exploded — shouting, grabbing her and then following her on his ATV as she ran to safety at a relative's home.