Jack Smith - the special counsel tasked with investigating former president Donald Trump's possible mishandling of classified documents at his Mar-a-Lago Club and residence and key aspects of the Jan. 6 probe - is a longtime federal prosecutor and seasoned investigator.

"Mr. Smith will begin his work as special counsel immediately and will be returning to the United States from the Hague," Garland said Friday afternoon in announcing his choice of Smith, who is currently serving as a war crimes prosecutor with the International Criminal Court. "Throughout his career, Jack Smith has built a reputation as an impartial and determined prosecutor who leads teams with energy and focus to follow the facts wherever they lead."

In a statement Friday, Smith promised to conduct the investigations and any possible prosecutions "independently."

"The pace of the investigations will not pause or flag under my watch. I will exercise independent judgment and will move the investigations forward expeditiously and thoroughly to whatever outcome the facts and the law dictate," he said.

Smith's career as a prosecutor began in Manhattan in the early 1990s, where he earned a reputation as a hard worker.

"I don't think I was very talented, but you field a lot of groundballs, you're a good shortstop," Smith once told the Associated Press about those early days.

He went on to spend nearly a decade as a federal prosecutor in Brooklyn.

Smith was a federal prosecutor on a case in which the defendant, Ronnell Wilson, was sentenced to death for killing two police officers. But a federal appeals court overturned the death sentence in 2010 on grounds that prosecution violated Wilson's constitutional rights by telling a jury that Wilson's refusal to testify during the penalty phase undermined his claims of remorse. Smith had told the jury that Wilson "has an absolute right to go to trial, put the government to its burden of proof, to prove he committed these crimes, but he can't have it both ways," according to a New York Times report at the time. The case continued for years until 2016, when a federal judge ruled that Wilson could not be sentenced to death because he was considered intellectually disabled.

Smith left the job in Brooklyn in 2008 to become a war crimes prosecutor at the ICC. Smith returned to the Justice Department in 2010, taking over the Public Integrity Section at a time when it had been battered by an embarrassing reversal of the conviction of Sen. Ted Stevens (R-Alaska).

At the time, he described taking a fiercely independent view of the job.

"If I were the sort of person who could be cowed - 'I know we should bring this case, I know the person did it, but we could lose, and that will look bad' - I would find another line of work," he told the New York Times. "I can't imagine how someone who does what I do or has worked with me could think that."

He left the agency in 2017 and returned to The Hague the next year.

At the ICC he was investigating war crimes committed in Kosovo.

Though the special counsel appointment begins immediately, Smith was not at Friday's announcement, due to a recent bike accident that required knee surgery.

He is a graduate of the State University of New York at Oneonta and Harvard Law School. He was widely recognized for his work having received the U.S. Department of Justice Director's Award as well as the U.S. Attorney General's Award for Distinguished Service.

Smith was previously vice president and head of litigation for the Hospital Corporation of America, one of the largest nonprofit health-care providers in the United States. Before that, from February 2015 to August 2017, he served as first assistant U.S. attorney and acting U.S. attorney for the Middle District of Tennessee.

Smith previously supervised the litigating process of complex public corruption cases across the country as the head of the Public Integrity Section. Before that, he coordinated investigations of foreign government officials for genocide and war crimes in the International Criminal Court's Office of the Prosecutor.

Before joining the ICC, Smith spent nearly a decade in the U.S. attorney's office for the Eastern District of New York, where he spent time as the head of criminal litigation. In that position, Smith oversaw about 100 criminal prosecutors working on varied areas including terrorism, violent crime and gangs, along with white-collar crimes.