U.S. Capitol Police Officer Brian Sicknick, who died the day after he engaged with the Jan. 6 rioters, had two strokes and died of natural causes, a medical report released Monday found.

The report, which was first obtained by The Washington Post , may complicate prosecutors case against the two rioters accused of using chemical irritants to assault Sicknick, 42, who collapsed after returning to his office that day and died about eight hours later. While the two men have been charged with assaulting the officer, they have not been charged in his death.