Deputies arrived at a trail off Y Road in Whatcom County, about 115 miles north of Seattle and near the border with Canada, on a Saturday afternoon to respond to reports of a group fight and a stabbing.
They found Dake Traphagen, a 69-year-old from Bellingham, and a group of other hikers, according to the Whatcom County Sheriff’s Office.
Traphagen told investigators that there had been an argument over right-of-way usage of the trail when the group was walking down and the biker was riding up, they said.
According to Traphagen’s version of events, the rider attacked him, and they wrestled to the ground, police said.
He allegedly told them he stabbed the biker with a pocket knife in self-defense.
It happened on March 6, but the sheriff’s office released details on the incident this week.
The cyclist had left the scene before deputies arrived, according to the sheriff’s office.
But they later responded to a home in Bellingham and found a 66-year-old man with multiple stab wounds, suffering from loss of blood, authorities said.
Deputies identified him as the mountain biker from earlier, and he was transported to a local hospital before being airlifted to Harborview Medical Center in Seattle with severe injuries, according to the sheriff’s office.
Several days later, detectives spoke with the rider.
He told them that he was riding uphill slowly when he encountered the hikers and asked them to move aside – citing difficult terrain and that he was strapped into his bike.
He said one of the hikers grabbed his handlebars, spun the bike to the ground and began hitting him. He realized later he was being stabbed not punched, investigators said.
He eventually escaped and fled home, according to the sheriff’s office.
After interviewing the mountain biker, authorities charged Traphagen with assault and possession of a dangerous weapon – which they said was a spring-loaded knife outlawed in the state.
Traphagen surrendered at the sheriff’s office on Tuesday, authorities said.
His bond was set at $1,000, according to court records.
A man who answered a call Thursday evening to the number listed on a business website for a Dake Traphagen from Bellingham, Wash., declined to comment and referred inquiries to his attorney, Angela Anderson.
She did not immediately respond to a Fox News request for comment.