Farmington has hired a former Mendota Heights police sergeant who was fired after authorizing an illegal search during the investigation of a drug overdose death. Bobby Lambert was sworn in as a patrol officer at Monday’s city council meeting, joining a 25-member police force. The county attorney’s office eventually declined to pursue charges against two men who were present during the overdose death, partly because of the illegal search, the decision said. In his report, arbitrator Richard John Miller chose to reserve judgment about whether the illegal search was a valid reason for firing Lambert. Farmington Police Chief Brian Lindquist said Tuesday that he was aware of Lambert’s firing and that he considers the illegal search “a training issue and not necessarily a dereliction of duty.” Lindquist said Lambert was the most experienced of the 200 applicants and that he emerged as the top candidate after a seven-stage process that includes internal reviews, interviews and hands-on scenario-based tests.