Loretta Lynch Sworn as Top U.S. Law Enforcement Official

President Barack Obama's choice for U.S. attorney general, Loretta Lynch, was sworn in at her new job on Monday, becoming the first African American woman to hold the post.

A career prosecutor known for trying high-profile anti-terrorism trials in New York, Lynch, 55, said she was "honored beyond words" to take over the job of the nation's top prosecutor.

Lynch vowed "to not just represent the law and enforce the law, but to use it to make real the promise of America -- the promise of fairness. The promise of equality. Of liberty and justice for all," she said in remarks after taking her oath.

Lynch served twice as U.S. Attorney for the Eastern District of New York, and has come to be known as a relentless federal prosecutor who put mobsters and terror suspects behind bars.

Her office has prosecuted more terrorism cases since the 9/11 attacks of 2001 than any other office.

Just last week, she announced a 25-year prison sentence for an American from New York who admitted he tried to join an al-Qaida group.

In previous years, she successfully prosecuted the terrorists who plotted to bomb the Federal Reserve Bank and the New York subway.

She also went after corrupt public servants and politicians in both parties, and won billions of dollars in settlements in fraud cases involving major banks.

The daughter of a librarian mother and a North Carolina minister father, Lynch attended Harvard College and then Harvard Law School.

Her father, who was seen in the Senate gallery during her confirmation vote, and at her hearings in the Senate Judiciary Committee, was also present Monday at her emotional swearing-in.

Lynch won confirmation just last week, after nearly a half-year-long delay, after Republicans refused to bring her nomination to a vote as a sign of opposition to her remarks that they interpreted as supporting Obama's immigration policies.

The delay in her confirmation was also driven by a standoff between Democrats and Republicans in Congress over abortion language tucked into a bill on human trafficking. 

Vice President Joe Biden officiated at Monday's ceremony, which was held in the conference room of the U.S. Justice Department.

"Ladies and gentlemen, it's about time. It's about time this woman is being sworn in," he said, alluding to the historically long delay, which had become a political sore point for many Democrats and as well as some Republicans in Washington.

The issue was resolved last week, clearing the way for what turned out to be confirmation by a comfortable margin.

Lynch takes over from Eric Holder, who in his six years as attorney general had a combative relationship with the Republican-led Congress, which voted to find him in contempt for not providing all the documentation lawmakers were seeking during a congressional gun trafficking probe.

She assumes the U.S. attorney general post -- just the second African American in the job after Holder -- as the nation wrestles with its response to a spate of controversial cases in which police and other law enforcement have used lethal force against unarmed black men.

Biden, who had warm words of praise for outgoing attorney general Eric Holder, said Lynch was "cut from the same cloth."

"She excelled in everything she's done from the time she was a child. She never had been limited by lower expectations of others," he said.

"She's shown resolve to prosecute and jail terrorists, mobsters and gang members. She's shown fidelity to the law and rooted out public corruption and shown determination to bring down financial fraudsters and child abusers and shown pursuit to bust the brutal human trafficking rings that she's encountered," Biden said.