The arrests are the closest federal prosecutors have come to identifying and charging anyone associated with the deaths that happened during and after the riot.
Five people died, including a woman who was shot by a police officer inside the Capitol. But many rioters are facing charges of injuring police officers, who were attacked with bats, sprayed with irritants, punched and kicked, and rammed with metal gates meant to keep the insurrectionists from the Capitol.
Investigators initially believed that Mr Sicknick was hit in the head with a fire extinguisher, based on statements collected early in the investigation, according to two people familiar with the case. But as they’ve collected more evidence, the theory of the case has evolved and investigators now believe Mr Sicknick may have ingested a chemical substance — possibly bear spray — that may have contributed to his death, officials have said.
Khater is the man in a video obtained by the FBI that showed him spraying Mr Sicknick and others with bear spray, according to court papers.
“Give me that bear (expletive), Khater said to Tanios on the video, according to court papers. Mr Sicknick and other officers were standing guard near metal bike racks, the papers say.
Khater then says, “they just (expletive) sprayed me,” as he’s seen holding a white can with a black top that prosecutors said “appears to be a can of chemical spray.”
After he sprayed the officers, they “immediately retreat from the line, bring their hands to their faces and rush to find water to wash out their eyes,” according to the court papers.
The two suspects were in custody, and the names of their lawyers weren’t immediately clear.
Mr Sicknick died after defending the Capitol against the mob that stormed the building as Congress was voting to certify Joe Biden’s electoral win over former president Donald Trump. It came after Mr Trump urged supporters on the National Mall to “fight like hell” to overturn his defeat.
The circumstances surrounding Mr Sicknick’s death remain unclear, and a final cause of death has not been determined. Capitol Police have said he died after he was injured “while physically engaging with protesters” and the agency’s acting chief said officials consider it a line-of-duty death.
Mr Sicknick collapsed later on and died at a hospital on January 7. The Justice Department opened a federal murder investigation into his death, but prosecutors are still evaluating what other specific charges could be brought in the case and the probe continues, officials have said.
The medical examiner’s report on Mr Sicknick’s death is incomplete. Capitol Police say they are awaiting toxicology results.
The FBI has already released about 250 photos of people being sought for assaulting federal law enforcement officers during the riot. Some have already been arrested, and the Justice Department said about 300 people have been charged with federal offences related to the riot.