BATH — Sagadahoc County Commissioners have hired a lawyer to investigate an allegation of sexual harassment against Sheriff Mark Westrum by a deputy.

Jonathan Goodman is a Portland lawyer with a background in police internal affairs investigations, according to a statement from Pamela Corrigan, the county administrator.

“It is essential to have a highly qualified and experienced individual handle the investigation so that the commissioners, the Sheriff’s Office and the public can have confidence in the findings,” Alan Houston, the commission chairman said in the statement.

The investigation is to begin immediately.

Commissioners voted earlier this week to look into the claim that Westrum made an advance toward a drug investigator and then turned hostile after the man recoiled.

Deputy Mark Damren said the sheriff touched him on his hip inappropriately. The alleged incident took place on a boat ride in August 2006.

Westrum has questioned the timing of the accusation. Damren is the subject of an investigation into whether he exceeded the allowed monthly minutes on his work cell phone, which Westrum said would be an improper use of the federal funds that support Damren’s job.

Damren was suspended for four days without pay in 2006 for having pornography on his work computer.