R Kelly has been arrested on federal sex trafficking charges

The R&B singer known as R. Kelly was arrested Thursday in Chicago on federal sex crime charges, marking another escalation in legal problems for the musician.

The U.S. Attorney's Office for the Northern District of IL and the U.S. Attorney's Office for the Eastern District of NY did not immediately respond to PEOPLE's requests for comment.

Kelly is now facing 18 federal counts, including child pornography, racketeering and kidnapping.

Greenberg says Kelly was aware of the federal investigations and the charges weren't a surprise.

Joseph Fitzpatrick, a spokesman for the U.S. Attorney's Office, confirmed to the Associated Press that authorities took Kelly, 52, into custody Thursday evening.

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Kelly pleaded not guilty to all charges, and he was later released on bail.

One of the alleged victims, identified in court documents as JP, said the assault took place in 2010 where Kelly "by the use of force or threat of force and. acted in such a manner as to threaten or endanger the life of JP".

The Cook County charges involve alleged abuse of a victim between the ages of 13 and 16. "It describes rules that Kelly had for the women, including not allowing them to eat or use the bathroom and not permitting them to look at other men and telling them to keep their heads down".

"Most, if not all of the conduct alleged, is decades old", Greenberg wrote in a statement posted on Twitter. It also names Kelly's business manager, Derrel McDavid, and another employee.

At least of the 5 victims held up an incident report dated 2009, in which she says she was held captive like the other victims who came forward before her. As of yet, the artist will have his initial arraignment in IL and then face a judge in NY. Kelly is being held at a downtown Chicago federal lockup.

An attorney for the 52-year-old Grammy Award victor says Kelly denies wrongdoing.

According to court records obtained by ET at the time, he was charged with 11 felony counts of sexual assault and sexual abuse related charges.

As you'll recall, the Ignition artist has been back in Chicago battling local sexual abuse charges, and delivering highly emotional interviews to anyone who will listen where he proclaims his innocence and demands justice.

Further details on the case are expected to be announced Friday. R. Kelly denied any wrongdoing and was released on bail.

The indictments demonstrate "the collaborative efforts of our criminal justice system", Foxx said.