Furthermore, the way that Cohen reported the $50,000 expense to the Trump Organization in January 2017 suggests the money may not have been paid out through traditional financial channels.
According to prosecutors, Cohen presented Trump executives with bank records for several of the expenses he incurred on Trump's behalf. But for his $50,000 payment to a tech company, Cohen provided no paperwork, just a handwritten sum at the top of one of the other bank documents.
The Trump Organization would later say that the $50,000 was a "payment for tech services." However, prosecutors say the $50,000 "was in fact related to work Cohen had solicited from a technology company during and in connection with the campaign."
A spokesman for the Trump Organization did not respond to questions from CNBC Wednesday about the payment. Trump's campaign, likewise, did not answer questions about whether it knew Cohen had paid a tech company $50,000 to aid in Trump's election bid.
Cohen's lawyer, Lanny Davis, also did not immediately respond to an inquiry about the money, and the White House did not respond to questions about whether the president was aware that Cohen was paying a tech company for election help.
It's not clear exactly when Cohen spent the money, only that it was during the campaign. And without knowing precisely what it was for, it's difficult to tell whether Cohen violated the law by not reporting it as a campaign expense.
The Trump campaign in 2016 had a savvy digital operation run by a relatively unknown online marketing specialist named Brad Parscale. Today, Parscale holds the top job on Trump's 2020 campaign team.
Cohen is not believed to have played any part in the official digital operations of the Trump 2016 campaign, nor did Cohen ever have a formal staff position on the campaign itself.
All of which only deepens the mystery of exactly what tech services Cohen was buying to help Trump's campaign.
In the 24 hours since Cohen pleaded guilty Tuesday, Davis, his lawyer, has repeatedly said that his client knows things that would be of interest to special counsel Robert Mueller, who is investigating the Russian attack on the 2016 U.S. presidential election.
Central to that investigation is the question of whether the Trump campaign conspired with the Russian government to sway the election in Trump's favor.
Cohen "is happy to tell the special counsel all that he knows, not just about the obvious possibility of a conspiracy to collude and corrupt the American democracy system in the 2016 election … but also, knowledge about the computer crime of hacking and whether or not Mr. Trump knew ahead of time about that crime and even cheered it on," Davis said during an appearance on MSNBC's "The Rachel Maddow Show" on Tuesday night.
Despite Davis' cryptic clues, there is nothing so far to indicate that the $50,000 in services that Cohen bought from the anonymous tech company were in any way related to the Russian cyber crimes and theft of emails that damaged Trump's Democratic opponent, Hillary Clinton.
It is also unclear whether the special counsel has interviewed Cohen yet. A Mueller spokesman declined to comment.
-- CNBC's Dan Mangan contributed to this report