A top FBI official confirmed Tuesday that the shooter at a recent rally of President Trump’s is linked to numerous hate-filled posts on two social media accounts, including a far-right networking site, Gab.

At a Senate hearing, the FBI deputy director, Paul Abbate, testified that Thomas Crooks is suspected of posting to a pro-Biden social media account “anti-immigrant” and “antisemitic” content. He then allegedly trolled Gab, under the user name “epic microwave,” and posted “pro-immigration, pro-lockdown, leftist views.”

That account often engaged in arguments with the conservative users on the platform.

Mr. Abbate told members of the Senate Judiciary Committee and the Homeland and Government Affairs Committee that the shooter posted more than 700 comments between 2019 and 2020. Mr. Abbate did not share any additional information regarding the pro-Biden account, but said that his agency would release more details as they are verified.

He also told members of the joint committee that the accounts “have differing points of view,” and that the FBI is working to verify that both accounts belong to the shooter.

Mr. Abbate said that the posts were made with the intent of inciting “political violence.” 

“While the investigative team is still working to verify this account to determine if it did in fact belong to the shooter, we believe it important to share and note it today,” he added. 

Mr. Abbate testified that this information was particularly important “given the general absence of other information to date from social media and other sources of information that reflect the shooter’s potential motivation and mindset.”

The FBI holds that despite numerous interviews, ongoing analysis of Crooks’s debit devices and credit cards, as well as the cooperation of his parents, his motivations remain largely unknown.

Meanwhile, members during the joint hearing grilled Mr. Abbate and the acting Secret Service director, Ronald Rowe Jr., over the shooting, demanding that agents be relieved of duty. Senator Hawley vehemently called for the resignation of various Secret Service employees.

“Who was the lead site agent who made the decision to leave the ATR building completely outside of the security perimeter? Who was that?” he said. “Has that person been relieved of duty?”

“If it wasn’t the lead site agent, who made that decision?” he added. “My question is, why don’t you relieve everybody of duty who made bad judgment? You’re right, I am zeroing in on someone, I’m trying to find somebody who is accountable here.”

Mr. Rowe told members of the committee that the operation was a “failure at multiple levels” for the Secret Service and the FBI.

“What I saw made me ashamed,” Mr. Rowe said. “I cannot defend why that roof was not better secured.”

Senator Johnson also pressed Mr. Rowe to make 13 agents and officers available to the committee for transcribed interviews, to which Mr. Rowe agreed.