A key prosecution witness said Monday she had videotaped, three-way sex twice with pop singer R. Kelly and an underaged girl, at his trial on 14 charges of child pornography.

Kelly, 41, and his alleged victim, who was 13 at the time, have denied being on a home video leaked to the Chicago Sun-Times and later on the Internet in 2002 that form the basis of the charges that could put the musician away for a maximum 15 years.

Lisa Van Allen said Monday that after she and Kelly met in late 1997, they filmed each other with the alleged victim on two occasions in 1999 and 2000, although prosecutors stressed that neither tape was the recording shown the jury at the trial.