James Comey: The Man at the Center of the Clinton Email Investigation

FBI Director James Comey started his news conference Tuesday in the boldest of fashions, explaining that no one else in government knew what he was about to say, which would include news with great national political and legal implications.

But this was not Comey's first high-stakes rodeo. The towering, 6-foot-8 Republican has served presidents from both parties and built a career on his daring ways.

Here's a closer look at the man who reprimanded former Secretary of State Hillary Clinton for her use of a personal email server, but also seemingly put an end to the question of whether any criminal charges will be filed:

How He Became One of America's Top Cops:

President George W. Bush appointed Comey deputy attorney general in 2003, at the height of tough legal questions surrounding the war on terror and the Patriot Act. Prior to that post, he served as the top federal prosecutor in New York City, where he took on a number of major terrorism and criminal cases.

"He is known as a straight shooter and fairly non-partisan, which is reflected in the fact that he was confirmed for his current position as FBI director by 93-1 vote [in the Senate]," ABC News senior legal analyst Sunny Hostin said.

His High-Profile Case Load and a Bedside Drama

Over the course of his career, Comey, 55, has been involved in a number of blockbuster cases. He prosecuted businesswoman Martha Stewart and mobster John Gambino, and handled the investigation and indictments of the suspects in the Khobar Towers bombing in Saudi Arabia. He appointed the special investigator to lead the probe into the leaking of CIA officer Valerie Plame's name, a politically charged inquiry that resulted in the conviction of Vice President Dick Cheney's adviser Scooter Libby.

And, most famously, Comey reportedly rushed to John Ashcroft's hospital bedside in 2004 to stand up to White House officials who were allegedly trying to obtain an extension of a controversial warrantless wiretapping program from the attorney general. Ashcroft had been hospitalized after gall bladder surgery, and Comey was serving as the acting A.G. in his place and had refused to extend the program.

"Jim always demonstrated great integrity and political independence from the White House, even if it made him unpopular," John Bellinger, former legal adviser to the National Security Council during the Bush Administration, told ABC News.

Connection to the Clintons

Comey's past head-to-head encounters with presidential administrations perhaps made him uniquely qualified to oversee the investigation into Clinton's controversial email practices, and it was not the first time he weighed in on matters relating to the Clinton's. In 1996, Comey served as deputy special counsel to the Senate special committee on the Whitewater investigation, chaired by Republicans at the time, which linked Hillary Clinton to the mishandling and destruction of documents.

Comey was also involved at both ends of the case of Marc Rich, a billionaire oil trader indicted for tax fraud and trading with Iran during the hostage crisis, who was later pardoned by President Bill Clinton during his final day in office in 2001. In a letter to the U.S. Senate, Comey describes working as both the lead prosecutor in New York on the original case against Rich in 1983 and then later, in 2002, overseeing criminal investigations into Clinton's last-minute pardons.

The investigations concluded there was no wrongdoing on the president's part, despite public outcry over evidence that Rich's ex-wife had donated to Hillary Clinton's Senate campaign.

"I have never seen him knuckle under to political pressure," Bellinger continued. "Jim is not motivated by politics but rather by seeking justice and doing the right thing."