Capitol Police Officer Brian Sicknick had two strokes before he died following the January 6th insurrection at the Capitol, according to a ruling from the D.C. Medical Examiner.

Sicknick’s manner of death was reported as natural. The cause was listed as “acute brainstem and cerebellar infarcts due to acute basilar artery thrombosis.”

The office, which released the report Monday, classifies a death as natural when “a disease alone causes death. If death is hastened by an injury, the manner of death is not considered natural.”

In a press release, Capitol Police say they accept the findings, but “This does not change the fact Officer Sicknick died in the line of duty, courageously defending Congress and the Capitol. The Department continues to mourn the loss of our beloved colleague. The attack on our officers, including Brian, was an attack on our democracy.”

The 42-year-old was sprayed with a chemical irritant, reportedly bear mace, at the Capitol around 2:20 p.m. on January 6th. At 10 p.m. that night, Sicknick collapsed at the Capitol and was transported to a local hospital where he died the next night.

Chief Medical Examiner Francisco J. Diaz told the Washington Post that the autopsy found no evidence he “suffered an allergic reaction to chemical irritants, which Diaz said would have caused Sicknick’s throat to quickly seize. Diaz also said there was no evidence of internal or external injuries.”

The Metropolitan Police Department is still investigating the case with Capitol Police and the FBI.

Two men, Julian Elie Khater, 32, of State College, Pennsylvania, and George Pierre Tanios, 39, of Morgantown, West Virginia, were arrested for assaulting Sicknick with the irritant during the insurrection.

The determination is likely to significantly inhibit the ability of federal prosecutors to bring homicide charges in connection with Sicknick’s death.

Sicknick was honored at the U.S. Capitol in February before his ashes were interred at Arlington National Cemetery. He joined the Capitol Police in 2008 and most recently served in the first responder’s unit.

“The United States Capitol Police will never forget Officer Sicknick’s bravery, nor the bravery of any officer on January 6, who risked their lives to defend our democracy,” the release said.

This story has been updated to add response from the U.S. Capitol Police.