Singer R. Kelly, already under indictment in Chicago on state charges of aggravated sexual assault and abuse, was arrested Thursday night by federal agents and accused of child pornography and other federal crimes, officials said.

Joseph Fitzpatrick, an assistant U.S. attorney in the Northern District of Illinois, said Kelly was arrested in Chicago on a 13-count federal indictment.

“The indictment includes charges of child pornography, enticement of a minor and obstruction of justice,” Fitzpatrick said.

The federal charges deepen the legal morass for Kelly, who had been dogged by allegations of sexual misconduct for decades but was acquitted on state child pornography charges in 2008.

Kelly, whose real name is Robert Kelly, already faces more than a dozen state felony charges related to sexual abuse accusations in Chicago involving four women, three of whom were underage at the time of the alleged crimes, prosecutors said.

He was charged with 10 state counts in February, with more state charges filed against him in May.