Who is FBI Director Christopher Wray?

FBI Director Christopher Wray testified in front of a House Judiciary Committee oversight hearing on Thursday, telling lawmakers that "there is no finer institution than the FBI, and no finer people than the men and women who work there and are its very beating heart."

His remarks came after Trump slammed the federal law enforcement agency on Twitter. 

"After years of Comey, with the phony and dishonest Clinton investigation (and more), running the FBI, its reputation is in Tatters - worst in History!" Trump tweeted Sunday. "But fear not, we will bring it back to greatness." 

Following Trump's critique, Wray sent out an internal letter to employees on Monday, a government source confirmed to Fox News.

In it, Wray wrote that he was "inspired by example after example of professionalism and dedication to justice demonstrated around the Bureau. It is truly an honor to represent you."

"We are entrusted with protecting the American people and upholding the Constitution and laws of the United States," Wray also wrote. "Because of the importance of our mission, we are also entrusted with great power, and we should expect – and welcome – people asking tough questions about how we use that power. That goes with this job and always has." 

The letter didn't mention Trump. 

Wray emerged from a list of former prosecutors, politicians and law enforcement officials interviewed by Trump to become director of the bureau. Here's what you should know about him. 

When was Wray installed as FBI Director? 

Wray was formally installed as the new director of the FBI on Sep. 28, after he was confirmed by the Senate on a 92-5 vote in August. All five nay votes came from Democrats. 

He was unanimously approved by the Senate Judiciary Committee in July, after he appeared before the committee. President Trump called Wray "an impeccably qualified individual" in a June statement

What did Wray do before he was confirmed by the Senate? 

Wray worked at the King & Spalding law firm, where he'd been a partner since August 2005, his Senate Judiciary Committee questionnaire said. 

Wray also represented New Jersey governor Chris Christie during the investigation into the George Washington Bridge lane-closing case, nicknamed "Bridgegate." Two former Christie aides were convicted of plotting to close bridge lanes to punish a Democratic mayor who wouldn't endorse the Republican governor.

What about Wray's time at the Department of Justice (DOJ)?

Wray worked as an associate deputy attorney general in 2001, before he was principal associate deputy attorney general from 2001 - 2003, his Senate Judiciary Committee questionnaire says. From 2003 to 2005, Wray worked as assistant attorney general for the criminal division under President George W. Bush. 

What do we know about Wray's career before working for the DOJ? 

Wray graduated from Yale University in 1989 before graduating from its law school three years later, the DOJ says online. He was an assistant U.S. attorney in Georgia from 1997 to 2001.

Before that, Wray was an associate at King and Spalding from 1993 to 1997, according to his Senate Judiciary Committee questionnaire. From 1992 to 1993, he was a clerk for Judge J. Michael Luttig, with the U.S. Court of Appeals for the Fourth Circuit. 

Fox News' Catherine Herridge and The Associated Press contributed to this report.