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Joel Greenberg, who U.S. Representative Matt Gaetz had referred to as his wingman, appeared in federal court wearing a dark blue prison jumpsuit on Monday to plead guilty to six federal charges, including sex-trafficking of a minor.

The former Florida tax collector, who is central to the investigation into whether Gaetz trafficked a 17-year-old for sex, also agreed to cooperate with prosecutors, which could spell trouble for the Republican congressman and one of former President Donald Trump's staunchest defenders.

Outside the courthouse in Orlando, Florida, Greenberg's lawyer, Fritz Scheller, said his client would honor his plea agreement if prosecutors sought information from him about Gaetz.

SCHELLER: "Does my client have information that could hurt an elected official? I guess this is just, you know, must-see television. You'll just have to wait and see."

A plane pulling a banner that read "Tick Tock Matt Gaetz" circled above the federal courthouse during Monday's plea hearing.

BRIAN BEUTE: "I sustained an eight-month-long string of attacks on my character."

Earlier, Brian Beute, who ran against Greenberg for Seminole County Tax Collector and helped initiate the investigation, held a press conference as Greenberg pleaded guilty to having letters sent to the school where Beute worked that falsely accused him of sexual misconduct with a student.

Beute's attorney, David Bear, also spoke to the media.

BEAR: "I am completely confident Joel is providing substantial assistance for very important players throughout the community who are committing crimes and think they can get away with it because they are powerful and wealthy and hopefully they won’t anymore."

Investigators are seeking to determine whether Gaetz had sex with the same 17-year-old Greenberg was accused of trafficking, according to a law enforcement source who spoke with Reuters.

Gaetz has not been charged with any crimes and has repeatedly denied wrongdoing.