The president's former fixer raked in millions claiming access and information to the new administration.
The nation's former top diplomat quickly ended the inquiry roughly two days later.
The meeting stands as the second instance of the president's eldest son working with foreigners to help win the 2016 election.
One of President Trump's personal attorneys had routinely said he could not be indicted per Department of Justice policies.
Rudy Giuliani said the preparation would be similar to the presidential debates in 2016.
The president's former personal attorney previously stated that a deal for a Trump Tower in Moscow was dead in January 2016.
Giuliani reacted to a report about a government informant talking to former Trump campaign aides in 2016.
Large swaths of the dossier remain unverified, but much as been revealed over the past year.