Authorities charge two men for assault on U.S. Capitol Police officer Brian Sicknick

Two men have been charged with assaulting U.S. Capitol Police officer Brian Sicknick with bear spray, as federal authorities inch closer to identifying what may have caused the officer’s death following the Jan. 6 assault on the Capitol by a violent mob loyal to former President Donald Trump.

Julian Khater, 32, and George Tanios, 39, were arrested Sunday. The FBI identified Khater as a man seen on video discharging canisters of the chemical irritant at Sicknick and other officers, according to an affidavit filed in federal court. He allegedly had retrieved that spray from a pack carried by Tanios, the court filing says.

Sicknick returned to Capitol Police headquarters later that day, when he collapsed and was admitted to the hospital. He died soon afterward, and his death became a rallying cry for lawmakers seeking justice for the attack on Congress.

But Sicknick’s cause of death has remained elusive. Capitol Police leaders have refused for weeks to disclose the status of his autopsy other than to classify it as a “line of duty” death. Early news reports that Sicknick was assaulted with a fire extinguisher and suffered blunt force trauma were later revealed to be untrue.

The absence of a homicide charge in Sicknick’s case more than two months after his death underscores the challenge facing investigators to prove a link between the bear spray assault and his death the following day.

Some experts have also said it could be difficult to ever make such a link to a level of certainty that would hold up in court, especially since police were also using chemical irritants to try to disperse the angry crowd.

Indeed, the affidavit an FBI agent submitted to obtain warrants to arrest Khater and Tanios says body-worn camera video from a Metropolitan Police lieutenant shows him spraying Khater after Khater unleashed spray on several officers, including Sicknick.

Khater made his initial appearance remotely Monday before a New Jersey-based magistrate, joined remotely by attorney Steven Altman, who Khater retained for his case. Altman urged the magistrate, Leda Wettre, to use her authority to press the government to ensure that Khater was transferred expeditiously to Washington D.C., a nod to the unusual fate that has befallen a few Capitol-related detainees who have sat in limbo for weeks.

Khater said little during the appearance but acknowledged the charges against him as well as the fact that a guilty verdict would likely result in his deportation, since he's not a U.S. citizen.

Tanios appeared briefly by video from a West Virginia jail at a hearing before a federal magistrate judge in Clarksburg, W. Va. The judge in that case set a bail hearing for Tanios Tuesday morning.

Sicknick is one of five people whose deaths have been linked to the storming of the Capitol in January. One participant in the disturbance, Ashli Babbitt, was shot and killed by a Capitol Police officer while trying to climb through a broken window in a lobby outside the House chamber. Three other people died during the chaos, with at least one reportedly trampled by the crowd.

Prosecutors and Capitol Police officials have indicated that numerous participants in the Jan. 6 riot deployed pepper spray, bear spray, mace and other chemical irritants at police. One Capitol Police Captain, Carneysha Mendoza, told a Senate committee Tuesday that she observed protesters deploy “military-grade CS” gas inside the Capitol itself.

Three officers, including Sicknick, were injured “as a result of being sprayed in the face with an unknown substance” by Khater, according to the charging document.

“The officers were [temporarily] blinded by the substance, were [temporarily] disabled from performing their duties and needed medical attention and assistance from fellow officers,” according to the FBI affidavit. “They were initially treated with water in an effort to wash out the unknown substance from their eyes and on their face. All three officers were incapacitated and unable to perform their duties for at least 20 minutes or longer while they recovered from the spray.”

It’s not clear if Sicknick’s death was a result of the spray, but the other two officers — identified as Edwards and Chapman — reported lasting injuries and said they believed it to be as strong as or stronger than pepper spray they had been trained to withstand.

One of the people who contacted the FBI about Tanios is identified as a former business partner who has known him for 15 years. That tipster also asserted that Tanios “embezzled $435,000 from their former business,” the FBI affidavit says, without offering further details.

Khater was arrested as he came off an airplane at Newark Airport in New Jersey, while Tanios was arrested at his residence in Morgantown, W.Va. Both men are expected to appear in federal court later Monday.