"There is nothing that can be done to investigate these allegations without the cooperation of both victims and witnesses," the Cook County state's attorney said.
A Chicago-area prosecutor on Tuesday asked that anyone who is alleging abuse by singer R. Kelly contact her office to investigate their claims, adding that families of two alleged victims have already come forward.
Cook County State's Attorney Kim Foxx made the request at a Tuesday press conference on the heels of the airing last week of the Lifetime docuseries, "Surviving R. Kelly,"which chronicles decades of the singer's alleged sexual misconduct.
"In order to have an investigation we have to have victims and witnesses who are willing to come forward with information," Foxx said. "Allegations of domestic violence or sexual assault require someone to say what they've seen, heard or experienced."
The six-part documentary that aired from Thursday through Saturday contains more than 50 interviews. It features testimony from women who accuse Kelly of mental, physical and sexual abuse, as well as interviews with associates and relatives of the singer.
Kelly, 51, has repeatedly denied claims against him. Representatives for the musician have declined to comment to NBC News about the series.
Foxx, the first African-American woman to lead the Cook County State's Attorney's Office, said at her news conference Tuesday, "There is nothing that can be done to investigate these allegations without the cooperation of both victims and witnesses. We cannot seek justice without you."
She said her office has been contacted by two families of two alleged victims. The families are in the Chicago area, she said.
The State Attorney's Office has not opened a formal investigation into the allegations.
Foxx said she watched "Surviving R. Kelly" and was "sickened" by it.
"I was sickened by the allegations. I was sickened as a survivor. I was sickened as a mother. I was sickened as a prosecutor," Foxx said. "I worked in this office for a number of years, including in 2008, so the allegations were not new to me."
Chicago police have made welfare checks at properties owned by Kelly in Chicago, including a recording studio, Foxx said, adding that the State's Attorney's Office has not been involved in those checks.