The R. Kelly prosecution finished its case Monday after star witness Lisa Van Allen testified about the inappropriate sexual relationship she was involved in, with the singer and the alleged 13-year-old victim.

Van Allen testified that, starting in late 1997, she participated in more than one threesome with the R&B singer and the girl on the sex tape. Both the alleged victim, who is now aged 23, and Kelly have denied that they are the ones on the video.

Van Allen, 27, got emotional and started crying as she described her three-way sexual encounters with the singer and the teen, some of which she claimed Kelly videotaped. During the three-hour testimony, she also told jurors that Kelly offered her $250,000 last year to recover a tape of one of the trysts. Defense attorneys challenged her credibility, calling her a liar, and accused her of plotting to extort money from the singer, which she denied. Eventually, she admitted she once stole Kelly’s $20,000 diamond-studded watch from a hotel.

That caused Derrel McDavid, Kelly's business manager, to call Van Allen in a statement “an admitted thief and liar who wouldn't know the truth if she tripped over it.”

Van Allen said Kelly told her the alleged victim was 16 when he introduced them to each other. The age of legal consent in Illinois is 17.

The three-way sex encounters took place in the same home in Chicago where prosecutors say the sex tape at the center of the case was made, Van Allen, who is now four-months pregnant, said. She described Kelly as obsessed with videotaping his sex trysts, testifying that he even carried around with him a duffel bag containing all of his homemade sex tapes.

Van Allen said she met Kelly at the making of a music video in Georgia about 10 years ago. She later appeared in several of Kelly’s music videos.

Kelly, 41, faces up to 15 years in prison if convicted of child pornography for allegedly videotaping himself having sex with the alleged victim.