Guido Antonini Wilson, a dual US-Venezuelan citizen now wanted by Argentina on money laundering charges, is alleged to have carried the money between Caracas and Buenos Aires.
Antonini was reported to be a passenger on a chartered plane that also carried officials from Venezuela's state oil company.
An unidentified passenger allegedly asked him to carry the cash in a suitcase through customs in Buenos Aires, prosecutors at the Miami court on Friday said.
US investigators later wired him with a recording device in Florida and gathered evidence against the alleged Venezuelan agents who pressured him to conceal the money's source, according to court documents.
Maionica admitted arranging calls between Antonini and a senior official in Venezuela's intelligence agency, which the FBI said it recorded.
He also admitted meeting Antonini and the other alleged agents - Venezuelans Carlos Kauffmann and Franklin Duran and a Uruguayan man, Rodolfo Wanseele.
They have pleaded not guilty and face up to 10 years in prison and $250,000 in fines if convicted at a trial set for March.
Another Venezuelan man charged in connection to the case has not been found.
Ruben Oliva, Maionica's lawyer, said his client had been in the US getting ready to take a cruise, and got involved in the scheme after he received a call from a senior Venezuelan official asking him to help Antonini Wilson.
Kirchner was elected president of Argentina in October 2007. Maionica is due to be sentenced on April 4.