AUBURN – Mayor Normand Guay said the head of the local police union made the report that led to his being stopped on suspicion of operating under the influence.

A police officer followed Guay for four miles Monday night before pulling him over, giving him a field sobriety test, handcuffing him and hauling him to the police station. Four other officers provided backup.

At the police station, a Breathalyzer test showed his blood-alcohol level was 0.01 percent, well below the legal limit for driving of 0.08 percent.

The day after the episode, tears came to the mayor’s eyes Tuesday as he discussed the ordeal. He suspects that the traffic stop may be related to acrimonious labor negotiations between the city and the police union.

“If that had something to do with this, and I’m not saying it did, it would sadden me terribly,” Guay said.

The mayor said he learned from the police report that two off-duty police officers made the call that led to his arrest.

The police report was not publicly available, but Guay identified one of the officers as Detective Chad Syphers, who is head of the police union. Syphers has declined to comment on the case.

Police Chief Richard Small said the original reason for the traffic stop was the mayor’s expired car registration. Guay was not cited for that because the state allows a 30-day grace period to renew registration.

Small commended his officers for following the proper procedure. “I have no indication that this was something personal,” he said.

The episode unfolded Monday after the mayor met with city councilors to discuss the labor negotiations. After the meeting he and Assistant City Administrator Mark Adams went to Gipper’s Sports Grill on Center Street.

Guay said he drank three beers but did not get drunk. He said he later returned to the City Building and saw a few police officers in the parking lot, where they had been protesting the dispute over their union contract.

As Guay was driving home about 25 minutes later, he realized an officer was following him. Officer Matthew Prince made the initial stop at 10:40 p.m., and four officers in three cruisers arrived to back him up.

The icing on the cake for the mayor was that he received a summons for drunken driving even after the test showed his blood-alcohol content was eight times lower than the limit set by the state for driving.

Guay was released but must appear in court on Sept. 17 on a charge of operating under the influence.

Small said that issuing a summons is the department’s way of protecting against lawsuits claiming false arrest.