On Sept. 4, 2017, according to his confession letter, Joel Greenberg called his friend Rep. Matt Gaetz with some bad news.

A teenager both men had paid to have sex with was underage, Greenberg claimed. Now, two sources tell The Daily Beast, a cooperating witness can confirm details of that call for one damning reason: He was in Greenberg’s office when the call took place.

The witness, “Big Joe” Ellicott—Greenberg’s longtime best friend and an employee at the Seminole County tax office—recently pleaded guilty to fraud and drug charges as part of a cooperation agreement with federal prosecutors…

While the sources did not know whether Ellicott had discussed the call with investigators, his account would likely be of critical interest, since it would match a key claim Greenberg made separately in a confession letter. That letter is now in the hands of federal agents, The Daily Beast previously revealed.