DENVER -- A Denver police detective is under investigation after a Jefferson County woman said he pulled a gun on her and her 11-year-old son during a traffic altercation.

Detective Michael Ryan, who works in the vice and narcotics bureau, is working a desk job until the investigation into the Aug. 29 incident is completed.

Christine Frappied told Jefferson County authorities that she was driving her son on Hampden Avenue, just west of Wadsworth Boulevard around 6 p.m., when she noticed a large pickup truck tailgating her. She said she tapped her brake to try and get the truck to back off.

Frappied said the pickup driver made an obscene gesture with his finger and then drove to the driver's side of her Volswagen Beetle and yelled something at her. She said she threw a cup of water out the window at him.

She called 911 on her cell phone after her son noticed the driver of the pickup had pulled a gun out and was displaying it.

Frappied got the license plate number of the truck and gave that to the dispatcher. Deputies eventually spotted the pickup further west on U.S. Highway 285 near Aspen Park.

Deputies said Ryan, 41, was driving the pickup and told them he had just gotten off work in Denver and was on his way home. He is under investigation for felony menacing according to the Jefferson County Sheriff's Office.

Contacted by a reporter Wednesday, Ryan said much of the information in the original complaint is inaccurate but he couldn't comment further on the advice of his lawyer and the Denver Police Department.