An alleged serial rapist was identified when one of his victims had the presence of mind to note his license plate number and provide it to Chelsea Police, leading to his identification in four other attacks, Suffolk County District attorney Daniel F. Conley said today.

JOSE S. CASTILLO (D.O.B. 5/17/76) of Chelsea was arraigned this morning in Suffolk Superior Court on seven counts of aggravated rape, four counts of indecent assault and battery, and a series of related offenses. The indictments, returned May 18 by the Suffolk County Grand Jury, charge Castillo with the rapes and attempted rapes of five different women in Chelsea last fall.

Castillo has been held on $20,000 cash bail since his March 22 arraignment in Chelsea District Court for one of the attacks. At the request of Assistant District Attorney Tara Burdman, Clerk Magistrate Gary D. Wilson imposed a new bail of $100,000.

Burdman, assigned to Conley’s Sexual Assault Unit, told the court that Castillo has been linked to a series of five early-morning attacks on women working as prostitutes in Chelsea during September and October of 2010.

“If the assailant thought we wouldn’t take these reports seriously, or if he thought they wouldn’t be reported at all, he was mistaken,” Conley said. “These were horrible crimes of sexual violence. Our office and Chelsea Police are committed to supporting the victims – no matter who they may and no matter their station in life – and holding a predator accountable for his actions.”

The circumstances of those attacks were similar, with the assailant picking the women up in a vehicle, driving them to a second location, threatening them with a knife, and raping or attempting to rape them. All of the victims later disclosed the attacks to Chelsea Police.

The victims gave various descriptions of their assailant as a Latino male, as having a small build, as speaking English with an accent, and as having metal caps on his teeth. Cumulatively, Castillo fits that description, Burdman said.

Burdman described five incidents, all in the early morning hours:

1. Sept. 16, 2010: Driving a light-colored minivan, Castillo allegedly picks up two women on Broadway. He drops one off and takes the second to an area near the Chelsea Soldier’s Home, where he produces a machete or large knife and rapes her in the vehicle’s middle row of seats. The woman ran screaming from the vehicle and sought help until a resident let her in and called Chelsea Police. The victim was later transported to Massachusetts General Hospital for a rape kit.

2. Sept. 22, 2010: Driving a green minivan, Castillo allegedly picks up a woman near Bellingham Square at about 2:20 a.m. He drives her to the area of Maple and Heard streets, where they move to the vehicle’s middle row of seats. He allegedly produces a knife and, during the course of a struggle, the victim is cut on her finger. She disclosed the attack to Chelsea Police and identified Castillo through a photo array in March.

3. Sept. 22, 2010: Later the same morning, Castillo allegedly picks up another woman and drives to the area of the Chelsea Soldier’s Home. They move to the vehicle’s middle row of seats, where he pulls a knife and rapes her. Castillo allegedly returned the victim to Bellingham Square, telling her that he was a gang member and not to disclose the attack. The woman later encountered some Chelsea Police and told them of the assault; she was taken to MGH but left before a rape kit was completed.

4. Oct. 10, 2010: Castillo approaches another woman in the early morning hours while driving a white minivan. After driving her to the area of the Chelsea Soldier’s Home, they move into the vehicle’s middle row of seats. Castillo allegedly pulls a knife and puts it to the victim’s throat, then rapes her. At one point, the victim’s cell phone rang and Castillo allegedly took it. Afterwards, he told her he was a member of the MS-13 street gang and would kill her if she told police. She did, in fact, tell police, and was later transported to Whidden Memorial Hospital for a rape kit.

5. Oct. 26, 2010: At about 1:30 a.m., Castillo, driving a dark blue minivan, allegedly lures another woman into his vehicle and drives to the area of the Chelsea Soldiers Home. They move to the middle row of seats, where he allegedly places an arm around her neck and a knife to her throat. When the woman said she was pregnant, he allegedly said he didn’t care and would stab her. The woman sustained a cut to her hand and finger during a struggle, but escaped and took down his license plate number. Later, she saw the same plate on a different colored minivan, and at another later time, again in a burgundy car. The woman flagged down a Chelsea Police officer, who notified the Chelsea Police Sexual Assault Unit. Officers stopped the car and the victim later identified Castillo as the attacker.

Castillo was represented today by attorney Shannon MacAuliffe. He will return to court on June 30.