DENVER >> Police in Colorado were working Wednesday to unravel a roadside mystery that began with a rollover crash and ended when one of the passengers was run down and killed.

Jesse Plouvier, 21, of Florence was charged with vehicular homicide after the hit-and-run incident early Sunday south of Colorado Springs, the El Paso County Sheriff’s Office said.

He is accused of killing 33-year-old Ian Saj, of Brush, who had survived the rollover crash.

Authorities say they’re baffled by the events that followed the rollover. Before troopers arrived, all three occupants got out unhurt and climbed an embankment to flag down help, Trooper Josh Lewis said.

A motorist later identified as Plouvier stopped to offer help before getting in a dispute with driver Randy S. Hardin, 26, of Colorado Springs, and refused to give the people a ride, authorities said.

“Plouvier got back in his car, drove off, turned around and headed back home,” sheriff’s spokesman Jeff Kramer said.

The three people from the wreck were still trying to flag down help when a vehicle struck Saj.

A tip led investigators to suspect that Plouvier was responsible. He was arrested after investigators searched his home in Florence looking for a vehicle with damage to a headlamp and front bumper.

Authorities wouldn’t say whether alcohol played a role in the events.

Plouvier was being held on $200,000 bail. No attorney was listed for him in court files. No phone listing could be found for Hardin.