A U.S. border guard has pleaded guilty to harassment for threatening to kill a Surrey, B.C., teenager during a road rage incident.

Joel J. Helle, 56, who works at the Blaine border crossing, was sentenced last week to one month of partial confinement.

According to court documents filed in Skagit County, the 17-year-old B.C. resident was driving northbound on the I-5 with his parents and two friends on his way back to B.C. from Seattle on April 23.

The teenager had just changed lanes when he noticed a black BMW following closely behind. The teen changed lanes again, away from the BMW, but it also changed lanes and moved in close to the teen's car, forcing him onto the shoulder of the road.

The BMW followed, at which point Helle got out of the BMW, struck the teen's window with his fist, then pulled out a badge and slapped it against the window. He then reached in and grabbed the teenager's neck, making statements like, "You are lucky I didn't shoot you."

Helle then let go of the driver, got back in his car and drove away.

Border guard thought he was intentionally targeted

In his defence, Helle said the teen changed lanes erratically and forced him off the road, even though Helle honked his horn repeatedly.

'After I wake up from such nightmares time and again, night after night, I always feel the scars in the neck with my fingers in the darkness' —Surrey, B.C., teenager

Helle claimed the teen was driving abnormally, leading him to believe "the driver's actions were intentional and that he was forcibly trying to assault or intimidate me on account of the performance of my official duties."

Helle said he has denied admissibility to thousands of arriving aliens in his work as a customs agent.

"I have initiated more adverse actions against arriving aliens than any other [Customs and Border Protection] officer in Blaine, Washington," his statement read.

"Many of these adverse actions have resulted in the aliens being barred from admission to the U.S. for a period of five years or longer."

Helle said he feared the Surrey teen might have been one of the "large number of Canadians" he'd taken enforcement actions against.

"During my employment as a CBP officer, while in my personal vehicle, I have been followed by a mental subject who had been stalking CBP officers as they leave ... at the end of their shift," the statement read.

"I am also aware of off-duty CBP officers who have been assaulted and murdered by subjects they had previously encountered during their duties."

Teen still haunted by incident

In his victim impact statement, the teen — whose name has not been released — said "it's still haunting me days and nights."

The teen said he feel nervous and tense driving on highways, and is "uneasy and fearful" driving across the border.

"At night I often dream of someone crushing my neck," the statement said. "After I wake up from such nightmares time and again, night after night, I always feel the scars in the neck with my fingers in the darkness."

He goes on to say tries not to let the incident affect his life, but "these days I find myself prone to angers and frustrations. Sometimes I have difficulties concentrating on studying and my grades have not been as good as before."

Helle has been on indefinite suspension without pay since the incident, and U.S. Customs and Border Protection is conducting an internal review.