The victims in both cases have positively identified Boccaleoni as their attacker in photo line-ups, sheriff?s Lt. Chris Spallino said.

But detectives are continuing to investigate his potential involvement in a series of other episodes on rural roadways in which women traveling alone reported being followed aggressively by a male driver who sometimes flashed his headlights, pulled alongside or feigned emergencies to try to get them to pull over.

One young woman was groped when she pulled over on Bennett Valley Road while driving home from Santa Rosa Junior College late one night last November, authorities said.

In another case in the Calistoga/Porter Creek road area, a man tried to force down the window of a woman?s car, they said.

In the most recent case, a woman on Sexton Road outside Sebastopol said her assailant persuaded her to pull over by saying her car was leaking fluid, tried to yank her out of the car, then grabbed her by the neck and threatened her if she resisted.

She managed to shove him off of her before throwing her car into gear and speeding away with the door open, authorities said.

Boccaleoni is still on probation for a San Francisco case in which four women were groped by a stranger during a single two-hour period in December 2005.

Police said Boccaleoni drove around the Marina District looking for women to approach for directions, then groped them when he did.

One of the women got Boccaleoni?s license plate number, leading to his arrest.

All four women identified him in a photo line-up, police said.

At the time, Boccaleoni told a Press Democrat reporter that it was a case of mistaken identity, and said he was a married father of four children, ?a family man.?

But he pleaded guilty to burglary the following summer in a plea agreement that included dismissal of sexual assault charges, a San Francisco Superior Court spokeswoman said.

Law enforcement and civilian sources who recalled his history or thought he resembled a police description and composite drawing from the recent Sonoma County incidents brought him to the attention of sheriff?s investigators on the case, Spallino said.

He had been under surveillance for about a week when sheriff?s deputies arrested him at his home late Tuesday night, he said.

Boccaleoni was arrested for suspected assault with intent to commit rape, false imprisonment and threatening a crime - all felonies.

He is being held in the Sonoma County Jail without bail.