Jack Smith, the US special counsel who on Tuesday filed a second federal criminal indictment against Donald Trump, is an Ironman-racing, Harvard grad with a reputation for winning tough cases against war criminals, mobsters and crooked cops.
Appointed last November by Attorney General Merrick Garland to take over two Justice Department investigations involving Trump, Smith has now secured two indictments against the former US president.
He secured a grand jury indictment of Trump on Tuesday charging him with crimes including conspiracy and witness tampering for Trump's efforts to overturn his 2020 election loss to now-President Joe Biden, which Trump continues to claim was the result of fraud.
"It was fuelled by lies," Mr Smith said in a brief two-minute press conference after filing the indictment.
"Lies by the defendant, targeted at obstructing a bedrock function of the US government: a nation's process of collecting, counting, and certifying the results of the presidential election."
That followed earlier charges against Trump in a federal court in Florida for mishandling classified documents.
When Smith is not busy competing in Ironman swim-cycle-run triathlon races, say former colleagues, he is a dogged investigator who is open-minded and unafraid to pursue the truth.
Trump has proclaimed his innocence. He has attacked Mr Smith on social media, on Tuesday calling the prosecutor "deranged Jack Smith."
"Why did they wait so long? Because they wanted to put it right in the middle of my campaign. Prosecutorial Misconduct!" Trump said on his Truth Social site.
Search for innocence and guilt
Mr Smith, a Harvard Law School grad, started as a prosecutor in 1994 at the Manhattan District Attorney's Office under Robert Morgenthau, who was best known for prosecuting mob bosses.
"There was just a real emphasis, from Morgenthau on down, on not just going after convictions," said Todd Harrison, an attorney at the firm McDermott Will & Emery who worked with Mr Smith in Morgenthau's office and later as a federal prosecutor.
"We were praised if we investigated something and demonstrated that the target of the investigation was innocent," Mr Harrison added.
In 1999, Mr Smith started working at the US Attorney's Office in Brooklyn.
Mr Smith was involved in the prosecution of Charles Schwarz, one of several former New York City police officers who were implicated in a high-profile police brutality case involving Abner Louima, a jailed Black inmate who had been assaulted by police with a broomstick.
Mr Smith also won a murder conviction against Ronell Wilson, a drug gang leader who murdered two undercover New York City police officers, though a federal appeals court vacated the death penalty verdict.
In 2008, Mr Smith left to supervise war crime prosecutions at the International Criminal Court in The Hague. He returned to the Justice Department in 2010 to head its Public Integrity Section until 2015.
More recently, Mr Smith returned to war crimes cases in The Hague, winning the conviction of Salih Mustafa, a former Kosovo Liberation Army commander who ran a prison where torture took place during the 1998-99 independence conflict with Serbia.
