An attorney for R. Kelly entered not-guilty pleas Monday on behalf of the R&B singer, who faces 10 counts of aggravated criminal sexual abuse, a spokeswoman for the Cook County, Illinois, state's attorney's office confirmed.

Kelly, who was charged Friday, is accused of sexually abusing four individuals, three of whom were under the age of 17 at the time of the alleged crimes, which took place between 1998 and 2010. One alleged victim formerly worked as a hairdresser for the singer, according to documents outlining the prosecution's case against Kelly.

Prosecutors say Kelly's youngest victim was 14 when the singer began sexually abusing her. He allegedly invited another victim to his studio after meeting her at a restaurant where she was celebrating her 16th birthday. Prosecutors allege the third underage victim met Kelly while seeking his autograph on the first day of his 2008 child pornography trial.

The trial resulted from a sex tape that had been mailed to reporter Jim DeRogatis, then a Chicago Sun-Times music critic. DeRogatis turned the tape over to authorities, who filed charges against the singer. At the trial, more than a dozen witnesses identified the person in the video as an underage girl, but the alleged victim and her parents did not testify. Kelly was acquitted on all 14 charges.

Kelly, 52, is listed as an inmate on the Cook County Sheriff's Office website. The singer has been in jail since he turned himself in to authorities late Friday. On Saturday, a Chicago judge set Kelly's bond at $1 million - Kelly's attorney, Steve Greenberg, has said the musician is struggling to come up with $100,000, the required 10 percent of the bond to get him released.

The singer's next court date is March 22.

Kelly's indictment followed weeks of heightened scrutiny against the singer in the aftermath of a widely watched Lifetime docuseries. "Surviving R. Kelly" took a sweeping look at decades of sexual misconduct allegations against Kelly and prompted Cook County State's Attorney Kim Foxx to make a public plea requesting potential witnesses or victims to come forward.

Kelly and his label, Sony subsidiary RCA Records, also parted ways amid the fallout from the docuseries.

The indictment Friday elicited cautious optimism from advocates, including the co-founders of #MuteRKelly, a campaign encouraging boycotts of Kelly's music. "Right now, I feel like we have just reached a point of reckoning," Kenyette Barnes, the campaign's co-founder, told The Post. "This is the culmination of years of activism and years of survivors coming forward and demanding accountability."

"This moment is an example of what a movement, when equipped with people, power and resilience, can achieve, but the work is not over," Tarana Burke, the founder of the #MeToo movement, said in a statement.

Artists including Lady Gaga and Chance the Rapper have recently apologized for working with Kelly. But as reported by The Post's Geoff Edgers last year, the music industry overlooked Kelly's alleged behavior for years - even amid the 2008 trial and earlier reports of inappropriate behavior, including his illegal 1997 marriage to his 15-year-old protege, Aaliyah. (The marriage was annulled after Aaliyah informed her parents. Aaliyah died in a plane crash when she was 22, in 2001.)

Kelly has long denied wrongdoing. Greenberg did not immediately respond to a request for comment Monday. But the attorney said publicly Friday that his client is innocent. "I think all the women are lying," he told a group of reporters, according to CBS Chicago.

This article was written by Bethonie Butler, a reporter for The Washington Post. The Washington Post's Elahe Izadi contributed to this story.