Former Attorney General Michael Mukasey took issue Wednesday with the "inexplicable" conduct by U.S. District Judge Emmet Sullivan at the sentencing hearing of former national security adviser Michael Flynn. 

Sullivan postponed Tuesday the sentencing of Flynn - citing his unfinished cooperation with Special Counsel Robert Mueller - but not before offering scathing comments, including asking prosecutors whether Flynn committed treason. 

In a hearing that Fox News' Catherine Herridge described as "one of the most dramatic" she has ever seen, Sullivan repeatedly asked Flynn's lawyers if he wished to withdraw his guilty plea over acccusations of misconduct by the FBI. 

Flynn stood by his guilty plea for making false statements to the FBI in a Jan. 2017 interview at the White House. 

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"Arguably, you sold your country out," Sullivan told Flynn, expressing "disdain" for Flynn's actions and emphasizing he would not accept a guilty plea from a person who believed they were innocent.

Reacting on "America's Newsroom," Mukasey - a former longtime federal judge in New York's Southern District - faulted Sullivan for failing to "restrain" himself with his comments and bringing up issues that were not relevant to the crime Flynn was being sentenced over. 

Mukasey said Flynn has an "exemplary record" of service in the military, was a first-time offender and cooperated with authorities, so he wouldn't have been facing a long sentence. 

"The reference to treason was totally inappropriate," he noted, explaining that Flynn's lobbying work for Turkey was not part of the charges and his work for Turkey ended before he started his work for the Trump administration. 

"The judge decided he couldn't restrain himself, and part of being a judge, as I recall it, is restraining yourself. ... The judge was convinced that there was something going on that he didn't know about, and that's not his business."

He added that the hearing did not reveal any new or "concrete" evidence of Trump-Russia collusion. 

Watch the full interview above.

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