An arbitrator has upheld the Mendota Heights' City Council's decision to fire Sgt. Bobby Lambert after he and officers conducted an improper search in February 2016 while responding to a drug overdose.

Arbitrator Richard J. Miller said in a March 2 decision that the city had the authority to terminate Lambert last June because he was still under a one-year probationary period. Lambert was a 20-year department veteran but had just been promoted to sergeant.

Lambert and his union, the Minnesota Public Employees Association, argued unsuccessfully that because Lambert was already an employee before the promotion, "just cause" was required to fire him.

On Feb. 4, 2016, Lambert and two officers arrived at a Mendota Heights home in response to a call about a possible drug overdose. Anthony Rancone was pronounced dead Feb. 5 after resuscitation efforts failed.

Lambert admitted he made mistakes during the investigation that followed, including searching the entire residence without a warrant.

The arbitrator found he also should have called an investigator to the scene and worn gloves during the search, which turned up $7,451 in cash plus drug paraphernalia.

The county attorney's office declined to charge two men present when the overdose occurred, the document said, partly as a result of Lambert's errors.

At a June City Council meeting, Lambert's supporters filled the chambers and passionately defended him, to no avail.

Lambert and the union alleged in a grievance that he was fired because city officials wanted to get rid of him. The union also said firing Lambert was "grossly disproportionate" to what he did wrong.

Earlier, Lambert had said his firing was retaliation for his 2012 demand that police look into the theft of a picnic table by other officers. The city spent $100,000 investigating that allegation.

Mike Aschenbrener was police chief during the incident. He oversaw a decade of tumult in the department, including three internal investigations of officers in 2016. Aschenbrener stepped down in December 2016 amid calls for new leadership, and Chief Kelly McCarthy was hired.

McCarthy said she hoped the department could move on and would try to ensure nothing like it occurs again.