The Los Angeles County Sheriff’s Department has opened a criminal investigation into the Motown legend Smokey Robinson, who was accused in a civil suit this month of sexually assaulting four women, the department said Thursday.

Mr. Robinson, 85, was sued earlier this month by four former housekeepers, who accused him of abusing them dozens of times over the years. His lawyer has denied the accusations. Now he is the subject of a criminal investigation.

“The Los Angeles County Sheriff’s Department Special Victims Bureau is actively investigating criminal allegations involving William Robinson a.k.a. ‘Smokey Robinson,’” Nicole Nishida, a spokeswoman for the department, said in a statement. “The investigation is in the early stages, and we have no further comment.”

The civil suit, filed in Los Angeles, identified the accusers only as Jane Does 1 through 4. They accused Mr. Robinson of raping them repeatedly over the years while they were employed cleaning several of his homes. The suit claimed that Mr. Robinson’s wife, Frances Robinson, has known about his sexual misconduct but failed to protect the women.

Mr. Robinson’s lawyer, Christopher Frost, said in a statement that the unnamed plaintiffs had “filed a police report only after they filed a $50 million lawsuit,” which he said that the police would be required to investigate.

“We feel confident that a determination will be made that Mr. Robinson did nothing wrong, and that this is a desperate attempt to prejudice public opinion and make even more of a media circus than the plaintiffs were previously able to create,” Mr. Frost said in a statement. “The record will ultimately demonstrate that this is nothing more than a manufactured lawsuit intended to tarnish the good names of Smokey and Frances Robinson, for no other reason than unadulterated avarice.”

The lawyers for the plaintiffs, John Harris and Herbert Hayden, said in a statement that they were pleased to learn that the sheriff’s department had “opened a criminal investigation into our clients’ claims of sexual assault against Smokey Robinson.”

“Our clients intend to fully cooperate with L.A.S.D.’s ongoing investigation in the pursuit of seeking justice for themselves and others that may have been similarly assaulted by him,” they said in the statement.