The special victims' unit of the L.A. County Sheriff's Department were in the early stages of the investigation as of Thursday, TheWrap has learned. The criminal probe followed a $50 million lawsuit against the music industry legend and his wife Frances Gladney filed May 5 by four former employees claiming sexual battery and assault.

PEOPLE can confirm that Smokey Robinson is facing a sexual assault investigation after four former housekeepers for the star sued him on May 6 for $50 million.

Motown legend Smokey Robinson is alleged to have raped four housekeepers who worked for him over the past 20 years. His wife is alleged to have covered it up.