A US Capitol Police officer who was injured during the storming of the building died from natural causes, a medical examiner's office has ruled.
© OtherBrian Sicknick died the day after the US Capitol riots
Brian Sicknick, 42, died the day after the 6 January insurrection which saw supporters of former president Donald Trump march on the Capitol building, sparking a riot.
Two men, George Tanios and Julian Khater, have been charged with assaulting Mr Sicknick and two other officers by spraying them with a chemical irritant.
Investigators initially believed Mr Sicknick had been hit on the head with a fire extinguisher, based on statements collected early in the investigation, according to two sources.
© ReutersOfficers carry the urn holding the remains of Brian Sicknick to lie in honour in the Capitol
They later thought he may have ingested a chemical substance, possibly bear spray, that could have contributed to his death.
However, the ruling found the officer had suffered two strokes and died of natural causes.
The ruling means a medical condition alone caused his death, rather than an injury, and it will likely make it hard for federal prosecutors to bring homicide charges in connection with his death.
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Lawyers for the men charged with assault had no comment.
Mr Sicknick was among five people who died shortly after or during the riot.
A large mob stormed the US Capitol building as Congress was voting to certify Joe Biden's election win over Mr Trump last November.
The former president had urged his supporters to "fight like hell" to overturn his defeat, making unsubstantiated claims of electoral fraud.