San Francisco's sheriff told an ethics panel weighing his fitness for office Thursday night that he reacted improperly when he grabbed his wife's arm during a quarrel several months ago.

Ross Mirkarimi was suspended without pay in March by Mayor Ed Lee after he pleaded guilty to a misdemeanor domestic violence charge in the incident.

The sheriff, whom the mayor is seeking to permanently remove from office, appeared before the panel for an hour.

Under meticulous questioning by Deputy City Attorney Peter Keith, Mirkarimi acknowledged that he had grabbed the arm of his wife, Eliana Lopez.

"I reacted intensely to a quarrel and I was wrong in the way I reacted," Mirkarimi said. He said that the action caused a large bruise on her arm.

Mirkarimi was sworn as sheriff in January after winning election in November.

His woes began on the afternoon of Dec. 31 when he and his wife became involved in an argument over whether she could travel to her native Venezuela with their three-year-old son.

Mirkarimi admitted bruising her arm with an overly firm grip. He pleaded guilty to misdemeanor false imprisonment in exchange for the dropping of other misdemeanor charges. He was sentenced to probation and counseling.

Lopez and her son departed for Venezuela March 25. A judge has given Mirkarimi permission to visit his son, but he still under a court-order to stay away from Lopez.

The hearing in front of the five-member commission set to resume Friday, with Mirkarimi scheduled to return to the stand. Mayor Ed Lee is also scheduled to testify.

This is the first time the panel has convened a trial-like hearing to determine whether an elected official should be removed from office.

It will forward its recommendation to the Board of Supervisors, which needs the votes of nine of 11 members to remove Mirkarimi.