When Robert Mueller was leading a US marine corps platoon in combat in Vietnam, Donald Trump was finishing college and about to go to work for his father, a New York City landlord, having received military draft deferments including for a diagnosis of bone spurs in his heels.

The contrasts between the two men are many, and were on full display yesterday when Mr Mueller testified about his long investigation of Mr Trump through the lens of Russia's 2016 US election interference.

Mr Mueller (74) served for 22 months as a special counsel appointed by the Justice Department, completing his inquiry in March. He has faced withering criticism from the Republican president, who has accused Mr Mueller of conflicts of interest and called his team of lawyers "thugs" and a "national disgrace".

Since Mr Mueller's 448-page investigative report was released by the Justice Department in redacted form on April 18, it has been widely reprinted and became a best-selling book, while Mr Trump (73) has launched regular Twitter attacks on it and its author.

On Monday, Mr Trump tweeted: "Highly conflicted Robert Mueller should not be given another bite at the apple. In the end it will be bad for him and the phony Democrats in Congress who have done nothing but waste time on this ridiculous Witch Hunt. Result of the Mueller Report, NO COLLUSION, NO OBSTRUCTION!"

Mr Mueller, the architect of the modern FBI and a long-serving federal prosecutor, has largely kept out of view since the report's release aside from a nine-minute appearance before reporters on May 29 at the Justice Department in which he said the inquiry had been conducted in "a fair and independent manner".

The weeks following have seen the Democrats dig into some of the unanswered questions in the report as they struggle to decide whether to pursue the impeachment process set out in the US constitution for removing a president from office.

After graduating from Princeton University, Mr Mueller served in the marine corps during the Vietnam War, leading a rifle platoon and receiving commendations including the Bronze Star.

He studied law at the University of Virginia and launched into a career of private practice and public service. In 2001, Mr Mueller, a Republican, was named to head the FBI by George W Bush and was unanimously confirmed by the Senate. He started work a week before the September 11, 2001, attacks on the United States. Barack Obama extended his service. By the time Mr Mueller left the position in 2013, his tenure was exceeded in length only by J Edgar Hoover's 48-year stint.

Mr Mueller's special counsel report said the investigation found insufficient evidence to conclude Mr Trump and his 2016 campaign engaged in a criminal conspiracy with Russia despite the numerous contacts. The report did not reach a conclusion on whether Mr Trump committed the crime of obstruction of justice but did not exonerate him. Attorney General William Barr, a Trump appointee, subsequently concluded the president had not committed obstruction of justice.

Longstanding Justice Department policy bars criminal charges against a sitting president.

Irish Independent