In 2016, Roger Stone communicated with a senior Trump campaign official about upcoming WikiLeaks disclosures.
According to CNN, Stone revealed as much Thursday in an opinion piece for the right-wing Daily Caller.
Stone published an exchange he had with Steve Bannon, then the chief executive of the Trump campaign.
The emails are among the documents in special counsel Robert Mueller's possession.
He's investigating whether Stone had an inside-track with WikiLeaks.
Mueller also wants to know whether Stone shared any of that information with then-candidate Trump or Trump's inner circle.