An unidentified woman is set to testify she engaged in sexual activity with R.Kelly and an underaged female, according to the Chicago Sun-Times. The woman's testimony was among the items discussed in secret hearings last year, the newspaper reported over the weekend. The judge in the case, Vincent Gaughan, will allow the testimony from the woman. "She was involved in a threesome with [the girl] and R. Kelly," a source said. The underaged girl is at the center of the case. She was the young female allegedly in the infamous sex tape with the R&B superstar; she's now in her '20s. Kelly was charged with a number of child pornography counts in 2002 when video tapes of the singer participating in lewd acts with what looked like minors surfaced. Jury selection of the often-delayed case begins this Friday. If found guilty, Kelly could face up to 15 years in prison.