(Updates to include sheriff's news conference, details from arraignment)
By Marty Graham
SAN DIEGO, Oct 15 (Reuters) - Former San Diego Mayor Bob Filner, who resigned after a string of sexual harassment allegations, pleaded guilty on Tuesday to charges of false imprisonment and battery involving three women.
A former Democratic congressman who was elected mayor of California's second-largest city last year, Filner was charged with felony false imprisonment and two misdemeanor counts of battery for placing a woman in a headlock and kissing or groping two others, prosecutors said.
Under the terms of a plea agreement, Filner will serve three months of home confinement and will be on probation for three years. He is also prohibited from seeking elected office again.
"This conduct was not only criminal, it was also an extreme abuse of power," said state Attorney General Kamala Harris, who filed the complaint against Filner. "This prosecution is about consequence and accountability. No one is above the law."
According to court papers, the felony count against Filner was filed because he used "greater force than was necessary" in restraining a woman. His lawyer said that he had put her in a headlock.
The misdemeanors included kissing a woman on the lips at a "Meet the Mayor" event and grabbing another woman's buttocks as she posed for a picture with the mayor at another public event.
Filner resigned in August as part of a settlement with the city over how to handle a lawsuit filed by a former press secretary, Irene McCormack Jackson, who was among at least 18 women who accused the 71-year-old politician of making unwanted sexual advances. So far, Jackson is only woman who has sued Filner.
The first Democrat elected to lead the relatively conservative Southern California city in years, Filner's fall from grace raises questions about which party voters will favor in a special election to choose his successor, set for next month.
At his arraignment on Tuesday, Filner wore a navy blue suit and a yellow tie, and appeared much thinner than he was when he tendered his resignation on Aug. 23. He said little during the hearing. He pleaded guilty and told the judge that he is a U.S. citizen.
After Tuesday's hearing, Filner's lawyer said the former mayor saw the plea agreement as an opportunity to move on from a scandal that threatens to overwhelm his legacy as a 10-term congressman who fought for civil rights and veterans.
"Mr. Filner profusely apologizes to each person he might have harmed," lawyer Jerry Coughlan said. "He admits he is guilty. ... He is a much more humble man now. He did not realize his behavior was as bad as it was."
Filner had apologized to San Diego residents but said no sexual harassment allegation against him had been proven.
Sheriff Bill Gore, who said his department conducted 90 interviews in its investigation of the former mayor said Filner's actions were embarrassing for San Diego.
"I saw what the city went through, I saw what the victims went through," said Gore, who is running for re-election next year in the non-partisan position. "It was a black eye for the city that we elected somebody who behaved this way."
In addition to Filner's sentence to home confinement and probation, he will not be able to vote, serve on a jury or own a firearm while he is on probation. He will be required to undergo mental health treatment, Harris said.
Filner also will not earn a public pension for the time between the commission of the felony, which Harris said was March 6, 2013, and the date of his resignation, Aug. 23. Details of the conditions of his confinement will be determined by probation officials.
In the race to replace him, City Councilman Kevin Faulconer is considered the presumptive Republican nominee. Former U.S. Marine Nathan Fletcher, who was a moderate Republican before switching parties in 2012, is the presumptive Democratic nominee. (Reporting by Sharon Bernstein in Sacramento and Marty Graham in San Diego; Writing by Sharon Bernstein; Editing by Cynthia Johnston, Gunna Dickson and Stacey Joyce)