A Sonoma Valley man was sentenced Monday to 10 months in jail for a series of gropings in which he walked up behind women and a teen and grabbed their breasts and buttocks.

Samuel Johnson Lyons, 37, preyed on unsuspecting victims in Sonoma and Petaluma between September 2011 and August, 2012.

Facing possible prison time, the former Peace Corps volunteer pleaded guilty this summer to a felony count of committing lewd and lascivious acts on a 14-year-old and four counts of misdemeanor sexual battery.

His lawyer sought probation so he could continue therapy for his sexual compulsion, but prosecutors argued he was a danger and needed to be punished.

Judge Jamie Thistlethwaite agreed Lyons should be locked up for "terrifying" women across Sonoma County.

"The activity you found yourself compelled to do absolutely won't be tolerated," the judge said in handing down the sentence.

Lyons, who was out on bail, stood silently beside his lawyer. He must turn himself in Jan. 25.

Under state sentencing laws, he could be released in June with credit for time already served. He will be required to register as a sex offender for the rest of his life.

Lyon's arrest ended a months-long investigation into reports from numerous women who said someone ran up from behind and grabbed them.

His last victim was assaulted as she was getting into her car outside a Sonoma grocery store. The others were groped as they walked along sidewalks or appeared in other public places.

Lyons' lawyer said his client suffered mental illness and was in treatment. He served in South America in the Peace Corps, he said.

You can reach Staff Writer Paul Payne at 568-5312 or paul.payne@pressdemocrat.com.