Mueller is now reportedly looking into the circumstances surrounding President Trump's firing of James Comey as Federal Bureau of Investigation director in May. "He was happy to answer all of their questions", Priebus attorney William Burck told Politico.
The former chairman of the Republican National Committee, Priebus was among several present and former West Wing staffers who were expected to be queried by Mueller's team, according to news reports.
Mueller's team has conducted interviews with a number of current and former Trump campaign and administration staffers as the Russian Federation probe continues.
Mueller is probing Russian interference in the 2016 election and whether there was collusion between Trump's campaign and Vladimir Putin's government. President Trump unceremoniously forced out or fired Priebus at the end of July.
Others include White House Chief Counsel Don McGahn, Communications Director Hope Hicks - and one of her predecessors, press secretary Sean Spicer.
"After he had spoken for a few minutes about leaks, Reince Priebus leaned in through the door by the grandfather clock and I could see a group of people waiting behind him", Comey's statement said. His voicemail box was full.
While Trump has repeatedly blasted Mueller's probe, White House lawyers have been eager to show they are cooperating with Mueller's requests.