Attorney General William Barr speaks alongside Deputy Attorney General Rod Rosenstein, right, Thursday, April 18, 2019, at the Department of Justice in Washington. (AP Photo/Patrick Semansky)
Washington CNN  — 

Special counsel Robert Mueller’s report raises fresh questions about Deputy Attorney General Rod Rosenstein’s dual roles as both witness in and supervisor of the special counsel investigation into possible obstruction of justice by President Donald Trump.

The report, a redacted version of which the Justice Department released Thursday, disclosed a previously unknown episode in which Rosenstein, resisted Trump’s efforts to get him to take the blame for the firing of FBI Director James Comey.

That event was examined as a key piece of Mueller’s investigation of Trump’s possible obstruction of justice, meaning Rosenstein was an important witness in a criminal probe he oversaw beginning in early 2017.

On the night of May 9, 2017, hours after Trump fired Comey, officials in the White House press office called the Justice Department to say the White House “wanted to put out a statement saying that it was Rosenstein’s idea to fire Comey,” according to the report.

Rosenstein told Justice Department officials that he wouldn’t participate in putting out a “false story,” he told the special counsel’s office.

Trump then called Rosenstein directly to say he was pleased with the Fox News coverage Trump was watching, and told Rosenstein he should have a press conference.

“Rosenstein responded that this was not a good idea because if the press asked him, he would tell the truth that Comey’s firing was not his idea,” the report says.

Meanwhile, according to a footnote in the report, the White House chief of staff at that time, Reince Priebus, was “screaming” at the Justice Department’s public affairs office in an attempt to force Rosenstein to conduct a press conference.

Later that evening, the White House press secretary at the time, Sean Spic