Grammy Award-winning singer R. Kelly, who already faces state sexual assault charges, has been arrested in Chicago on federal charges after having been indicted there and in Brooklyn, New York, a law enforcement source said on Friday. The source, who requested anonymity because the indictments were still under seal, declined to characterize the nature of the charges. NBC News, citing unidentified law enforcement officials, said they were for alleged sex crimes. Kelly, 52, an R&B singer, was arrested on Thursday by New York police detectives and investigators with the Department of Homeland Security, and is expected to appear before a judge in Chicago later on Friday, the law enforcement source said. "He's expected to be arraigned today in federal court in Chicago and at later date in Brooklyn," the source said. Kelly faces a 13-count federal indictment in Chicago and five counts in Brooklyn, the source said, adding that both indictments remain under seal. Last month, the singer pleaded not guilty to 11 new felony counts of sexual assault and abuse at a Cook County, Illinois, court hearing, after state prosecutors expanded an indictment against him. The R&B singer has vehemently denied abuse allegations for decades. In 2008, he was tried on child pornography charges and found not guilty. The Chicago Sun-Times said Kelly's attorney Steve Greenberg, on Thursday confirmed the arrest, but declined to give details. Greenberg was not immediately available for comment. The Cook County charges involve alleged abuse of a victim between the ages of 13 and 16. The accusations center on someone identified only as J.P. and the crimes are alleged to have taken place between May 2009 and January 2010. Kelly could face up to 30 years in prison if convicted on those charges. In February, Kelly pleaded not guilty to charges that he sexually assaulted three teenage girls and a fourth woman. The charges were brought after seven women, including his ex-wife, appeared on a Lifetime television documentary and accused him of emotional and sexual abuse. The singer, known for such hits as "I Believe I Can Fly" and "Bump N' Grind," spent a weekend in jail on the sex charges before being released on $100,000 bail on Feb. 25. — Reuters