Hawaii Sen. Mazie Hirono ripped into Attorney General William Barr with a nonstop line of questioning about his actions related to the FBI's Russia investigation on Wednesday.

Barr appeared to testify before the Senate Judiciary Committee about his oversight of the investigation and the special counsel Robert Mueller.

"You lied to Congress," Hirono said to Barr, pointing specifically to testimony he gave to the House Appropriations Committee last month that appears to contradict recent revelations of a rift between him and Mueller.

"Please, Mr. Attorney General, give us some credit for knowing what the hell is going on around here with you," Hirono later said before being cut off by Republican Sen. Lindsey Graham.

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In a tense exchange on Wednesday, Democratic Sen. Mazie Hirono laid into Attorney General William Barr and accused him of lying to Congress when he testified before the Senate Judiciary Committee about his oversight of the special counsel Robert Mueller and the Russia investigation.

"You lied to Congress," Hirono said to Barr on Wednesday. The Hawaii senator pointed specifically to Barr's testimony before the House Appropriations Committee in April.

At the April hearing, Rep. Charlie Crist asked Barr whether Mueller supported his conclusion in the obstruction case.

"I don't know whether Bob Mueller supported my conclusion," Barr replied.

Crist also asked Barr about reports at the time that members of Mueller's team were frustrated "at some level with the limited information included in your March 24 letter — that it does not adequately or accurately, necessarily, portray the report's findings."

"Do you know what they're referencing with that?" Crist asked.

"No, I don't," Barr said.

But on Tuesday, it surfaced that Mueller sent Barr a letter expressing frustration at the way the attorney general characterized the special counsel's findings in the investigation.

Read more: Barr went to incredible lengths to argue why a key interaction between Trump and Don McGahn was not obstruction

On March 24, Barr sent a letter to Congress laying out his "principal conclusions" about Mueller's findings, which were contained in a final report the special counsel submitted to Barr two days earlier. Barr said Mueller's team did not find sufficient evidence to charge President Donald Trump or anyone associated with his campaign for conspiring with the Russian government.

Barr also said prosecutors did not make a "traditional prosecutorial judgment" on whether Trump obstructed justice but that he determined there was not enough evidence to charge Trump with obstruction.

The next day, Mueller sent Barr a letter expressing concern with the way Barr had interpreted his findings. Two days later, on March 27, Mueller sent Barr a second letter saying the attorney general "did not fully capture the context, nature, and substance of this Office's work and conclusions" in his March 24 letter.

Shortly after, The New York Times and The Washington Post reported that members of Mueller's team were frustrated with the way Barr had portrayed their findings, especially in the obstruction case, in which they reportedly believed the evidence was "alarming" and "significant."

Hirono told Barr that although he claimed he didn't know whether Mueller supported his conclusions, "you knew, you lied, and now, we know."

Read more: Here's Mueller's full letter to Barr objecting to the attorney general's description of the special counsel's findings in the Russia probe

Hirono went on to criticize Barr's sweeping view of executive power and the presidential-pardon power, pointing to a 19-page memo he wrote last year arguing that the president cannot be guilty of obstruction.

"From the beginning, you were addressing an audience of one," Hirono said as Barr listened silently. "Now, we know more about your deep involvement in trying to cover up for Donald Trump. America deserves better. You should resign."

Hirono went on to ask Barr whether he felt Trump's actions outlined in the obstruction probe were appropriate, even if they were not criminal.

When Barr tried to answer her questions or asked her to clarify what she was asking, she repeatedly interrupted him.

"I think you know what I'm talking about," Hirono said. "Please, Mr. Attorney General, give us some credit for knowing what the hell is going on around here with you."

Hirono was then interrupted by South Carolina Sen. Lindsey Graham, the Republican chairman of the committee.

"Listen, you've slandered this man," Graham began to say.

"I do not think that I'm slandering anyone," Hirono replied.

"You've slandered this man from top to bottom," Graham said. "So if you want more of this, you're not going to get it. If you want to ask him questions, you can."

Hirono replied: "You certainly have your opinion, and I have mine."