A close friend and former government employee of Joel Greenberg, Joe Ellicott, is set to plead guilty to conspiracy to commit wire fraud and distribution of a controlled substance in the latest development in an investigation that includes a probe into allegations of possible sex trafficking of a minor by Florida Congressman Matt Gaetz, which he vehemently denies.

While Greenberg is not named, according to court documents unsealed overnight, Ellicott is set to plead guilty to working with a “government official” who assumed office in 2017 to commit wire fraud by facilitating bribery connected to government contracts that were signed by the “public official” who took office in 2017.

Ellicott had been cooperating with the prosecutors for months prior to being charged this week, according to a person familiar with the matter.

Greenberg, a one-time close ally of Gaetz who pleaded guilty last year to multiple federal crimes including sex trafficking of a minor, took office as Seminole County Tax Collector in 2017.

Last May, Politico reported that investigators were seeking information from close associates of Greenberg, including Gaetz and long-time friend Joe Ellicott. A subpoena received by one associate allegedly stated that the grand jury is investigating alleged crimes “involving commercial sex acts with adult and minor women as well as obstruction of justice.” It also requested any communications, documents, recordings and payments the individual had with Ellicott, Gaetz and Greenberg from 2016 until now, according to Politico.

In a statement responding to Ellicott pleading guilty, Gaetz’s chief of staff Jillian Lane Wyant told ABC News: “After nearly a year of false rumors, not a shred of evidence has implicated Congressman Gaetz in wrongdoing. We remain focused on our work representing Floridians.”

Ellicott is also set to plead guilty to the distribution of a controlled substance. According to court documents, Ellicott sold Adderall to others for at least two years including to one unnamed person who paid him a total of $5,000.

In one payment made over Venmo, the purchaser paid Ellicott for the drugs but wrote in the memo line “2 hour full body massage” to conceal the nature of the transaction, according to prosecutors.

Ellicott, who was also on the tax office payroll as an assistant deputy tax collector, has a long history with Greenberg; he was a groomsman at the former tax collector’s wedding and the pair co-hosted a local sports-themed radio show before Greenberg ran for office. Ellicott had been cooperating with the prosecutors for months prior to being charged this week, according to a person familiar with the matter.

Ellicott’s lawyer declined to comment.

Ellicott could emerge as a key witness in the ongoing sex traffic investigation, and appears to have information that may be damning to others beyond Greenberg, sources say.

As ABC News previously reported, in a private text exchange over the encrypted messaging app Signal, Ellicott allegedly told Greenberg in August 2020 that a mutual friend was worried she could be implicated in the investigation into the sex ring involving a minor.