Producer London on Da Track‘s mother, Cheryl Mack, was reportedly called on by prosecutors to testify against R. Kelly in the singer’s ongoing New York sex trafficking trial.

On Sept. 17, Mack, who used to work as an assistant for Kelly, took the stand and told jurors that she witnessed R. Kelly engaged in a sexual act with one of the women he is accused of physically and mentally abusing, according to Reuters.

Mack recounted an instance where the woman started to massage Kelly while backstage at a show in Connecticut. “That was kind of my cue to leave,” Mack said. “I was very uncomfortable.” As Mack exited, she said she saw the woman begin to move her head toward the singer’s crotch.

Mack’s testimony reportedly also included allegations that spoke to Kelly’s need for control. She testified about a situation in 2015 where Kelly accused her of wrecking a party for Kelly’s former stylist, Kash Howard. Out of anger, Kelly allegedly made Mack write an “apology letter,” in which she was forced to lie about taking money from booking agents.

“I apologized out of fear,” Mack said. Numerous people in Kelly’s entourage have confirmed that he made them write apology letters out of anger and as a means to skirt his own responsibility.

Kelly’s trial will resume on Monday (Sept. 20). He has been charged with one count of racketeering and eight counts of illegally transporting people across state lines for prostitution. The indictment against the singer accuses him of grooming underage and adult women via abuse and fear for nearly two decades, including singer Aaliyah who he married when she was only 15 and possibly impregnated.

The “Down Low” singer has an uphill legal battle as he also faces sex-related charges in his home state of Illinois and Minnesota.