R. Kelly’s federal trial in Chicago that starts Monday is in many ways a do-over of his 2008 state child pornography trial, at which jurors acquitted the singer on charges that he produced a video of himself when he was around 30 having sex with a girl no older than 14.

There’s one big difference: This time, prosecutors say, she will testify.

Kelly, 55, goes into Chicago federal court already sentenced by a New York federal judge to a 30-year prison term for a 2021 conviction on charges he parlayed his fame to sexually abuse other young fans.

Among the most serious charges the Grammy Award winner faces at his federal trial is conspiracy to obstruct justice by rigging the 2008 trial, including by paying off and threatening the girl to ensure she did not testify.

Testimony by the woman, now in her 30s and referred to in filings only as “Minor 1,” will be pivotal. The charges against Kelly also include four counts of the enticement of minors for sex — one count each for four other accusers. All are also slated to testify.

Even just one or two convictions in Chicago could add decades to Kelly’s New York sentence, which he is appealing. With the New York sentence alone, Kelly will be around 80 before qualifying for early release.

Prosecutors at the federal trial plan to play the same VHS tape that was “Exhibit No. 1″ at the 2008 trial. While it was the only video in evidence 14 years ago, at least three other videos will be entered into evidence at the federal trial.