Police officer Brian Sicknick died on January 6th defending the Capitol. It was believed Sicknick was beaten to death by assailants from the Trump-inspired mob. But The New York Times reports the F.B.I. now has a different theory and an assailant.

In a significant breakthrough in the case, investigators have now pinpointed a person seen on video of the riot who attacked several officers with bear spray, including Officer Sicknick, according to the officials. And video evidence shows that the assailant discussed attacking officers with the bear spray beforehand, one of the officials said.

But the F.B.I. doesn’t yet know the name of the assailant. The Times adds:

On Jan. 7, when Officer Sicknick died, the Capitol Police issued a statement that said he “was injured while physically engaging with protesters,” and then “returned to his division office and collapsed.” He succumbed to his injuries at the hospital.

The Washington Post reports investigators have determined Sicknick did not die from “blunt force trauma.”

A statement issued by Capitol Hill Police on Friday said, “We are awaiting toxicology results and continue to work with other government agencies regarding the death investigation.”

If the spray proved to cause a fatal reaction, it might not be enough to bring murder charges, according to the Post.

The video could offer prosecutors a path to charging someone in connection with Sicknick’s death — though they still have to identify the assailant and would then have to establish that the spraying proved fatal. Prosecutors, instead, might consider bringing assault charges.