The mastermind of a contract-steering scheme captured in brazen emails with the CEO of the Chicago Public Schools admitted his role Tuesday and could land in prison.

And with SUPES owner Gary Solomon’s admission, “I plead guilty, sir,” the stage is now set for former schools CEO Barbara Byrd-Bennett to be sentenced for defrauding Chicago students.

The last of the three to plead guilty in the scandal that ousted Byrd-Bennett in April 2015, Solomon admitted that he and his business partner, Thomas Vranas, plied Byrd-Bennett — their former employee — with meals, sports tickets and the promise of a 10 percent kickback on any business she steered from CPS or any other school district.

The plot began before she even assumed a top-level job at CPS in 2012, and continued after Mayor Rahm Emanuel elevated her to schools CEO. In emails, they promised to pay the bulk of her proceeds as a “signing bonus” once she left CPS and returned as their employee, but she also wanted college funds for her beloved twin grandsons, writing, “I have tuition to pay and casinos to visit (:”

Assistant U.S. Attorney Megan Church said that Solomon encouraged a reluctant Byrd-Bennett to join CPS in 2011, explaining “that it would be good for the SUPES entities . . . good for Byrd-Bennett, and good for CPS and the city.”

Indicted last October on 23 charges, Solomon pleaded guilty Tuesday to honest services wire fraud.

That charge carries a maximum sentence of 20 years in prison. Sentencing guidelines outlined in his plea deal appear to put the 48-year-old married father of three in the 10-11 year range. His sentencing hearing before U.S. District Judge Edmond Chang is set for March 24.

An attorney also entered a guilty plea on behalf of Solomon’s defunct companies, The SUPES Academy LLC and Synesi Associates, LLC.

Solomon exited the Dirksen Federal Courthouse, passing by reporters.

Solomon has no criminal background, but the Chicago Sun-Times has detailed his past of being forced out of Niles West High School for “immoral and unprofessional” conduct, including allegations he kissed a female student; covered up student alcohol and drug use; and sent emails to vulnerable students that were “sexually suggestive” and used a slew of racist terms.

The plea deal hinges on an October 2012 $2 million contract, the first of three no-bid deals handed to SUPES, the company Solomon and Vranas ran in Wilmette. But the contract that attracted the attention of the CPS inspector general was a $20.5 million no-bid deal for principal training that Byrd-Bennett inked a month after shuttering a record 50 schools.

Within days of federal subpoenas landing in April 2015 at CPS, Byrd-Bennett stepped down. Then within days of being indicted, she pleaded out, agreeing to a reduced sentence of about seven years for cooperating, and offered a tearful apology to the children of Chicago.

Vranas, who met Solomon as a Niles West student, pleaded guilty in April to a conspiracy count that carries a five-year maximum sentence but could be reduced by a third.

Sentencing for both Vranas and Byrd-Bennett have stalled pending Solomon’s case, which seemed to be headed for trial. Hearings could be set when they return before Chang next week.

The three owe $254,000 in restitution, according to the government.

All three defendants still face a civil lawsuit filed by a broke Chicago Public Schools seeking to claw back at least three times the amount it believes it’s lost to fraud. CPS paid SUPES and Synesi more than $15 million.