Two men have been charged with assault on the U.S. Capitol Police officer who was killed during the Jan. 6 riot at the U.S. Capitol, although authorities are not certain whether their actions caused his death.

The men are the first to be charged in relation to the officer, whose cause of death has not yet been officially determined.

Julian Elie Khater, 32, of Pennsylvania, and George Pierre Tanios, 39 of Morgantown, West Virginia, were arrested Sunday. They are accused of spraying Officer Brian D. Sicknick with bear repellant, according to The Washington Post. Both men are expected make their first appearance in federal court Monday on nine assault-related charges, including assault with a deadly weapon.

The charges extend to alleged assault on another U.S. Capitol Police officer, identified in court documents as C. Edwards, and a D.C. police officer identified as B. Chapman.

Aside from the alleged assault on Sicknick, Khater and Tanios also face several counts of civil disorder and obstruction of a congressional proceeding, the Post reported.

Each could face 20 years in prison if convicted.

The men were identified from photos of the mob scene released by the FBI, which were taken from surveillance and body cam footage and later recognized by people who knew them.

Video recorded during the mayhem show Khater telling Tanios to “Give me that bear s---” as they confronted officers at the Lower West Terrace of the Capitol, the Post reported. Sicknick was among a small cadre of officers standing guard behind metal bicycle racks, according to the arrest report.

At one point in the video, Khater is seen spraying Sicknick and two other officers in the face with a canister of bear spray, the Post reported, citing the arrest report.

The officers who were sprayed immediately retreated from the front line of defense to seek water to rinse out their eyes, according to charging documents.

Sicknick, 42, was later hospitalized and died one day after the assault carried out by supporters of former President Donald Trump who were sparked by months of false claims that widespread voter fraud got Joe Biden elected and cheated the incumbent out of a second term.

Some of the attackers in the crowd wielded sledgehammers, baseball bats, hockey sticks, crutches and flagpoles, the Post reported. The House and Senate had convened in joint session Jan. 6 to confirm Biden’s Electoral College victory when the rioters stormed the building in an attempt to overthrow the proceedings.

Sicknick was among five people who died during the uprising. Four were civilians, three of whom suffered health-related emergencies. One woman was shot dead by an officer after she tried to enter the building through a broken window.

In early February, Sicknick’s remains were honored in the Capitol Rotunda, where President Biden, first lady Jill Biden and lawmakers paid their respects to the 13-year Capitol Police veteran.

It remains unclear how Sicknick died.

Early news reports said the officer was hit by a fire extinguisher, but investigators later determined Sicknick did not die of blunt force trauma.

Capitol Police officials said Sicknick “was injured while physically engaging with protesters” and collapsed after the riot, an account backed up by then-Acting U.S. Attorney General Jeffrey A. Rosen.

This is a developing news story. Please stay with AJC.com for the latest updates.