MOUNTLAKE TERRACE — A former Mountlake Terrace police commander has been given a traffic ticket and a $550 fine in connection with his drunken-driving arrest earlier this year.

Don Duncan, 50, was cited for second-degree negligent-driving, court records show. Duncan paid the fine in November.

The case wasn’t strong enough to take to trial on the initial DUI charge, Marysville City Prosecutor Al Treacy said.

The Snohomish County Prosecutor’s Office referred the case to Treacy to avoid a conflict of interest.

Duncan worked for the Mountlake Terrace Police Department for nearly 18 years.

He was fired after an internal investigation into the circumstances surrounding his arrest.

Duncan has repeatedly said that he wasn’t under the influence when he was pulled over. He has been appealing his termination, with hearings scheduled this month and next.

In his firing, city officials said Duncan showed poor judgment in the hours and weeks after his arrest.

Duncan was on call the night of Jan. 31 when he was pulled over by a Washington State Patrol trooper near Lake Stevens and arrested for drunken driving.

Just after 3:15 a.m., hours after being arrested, Duncan took a breath test and reportedly blew a .055 and .058. The legal limit to drive in Washington is .08.

It wasn’t possible to prove that Duncan was above the legal limit when he was arrested. Calculations based on average alcohol burn-off rates show Duncan allegedly was “hovering around the legal limit,” Treacy said.

Treacy also knew the case could come under scrutiny. Previous incidents where people in public life — including a former Snohomish County judge — have been arrested for DUI and not convicted have caused controversy.

“Not every case you can take to trial,” Treacy said. “It’s been a long process, negotiating and dealing with other facts that came to light after the charging decision.”

Rikki King: 425-339-3449; rking@heraldnet.com.