What did the D.C. medical examiner determine was the cause of death for Brian D. Sicknick and when was that finding released (2021)?

Checked on January 10, 2026
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Executive summary

The District of Columbia Office of the Chief Medical Examiner ruled that U.S. Capitol Police Officer Brian D. Sicknick died of natural causes — specifically "acute brainstem and cerebellar infarcts due to acute basilar artery thrombosis" — and disclosed that finding on April 19, 2021 [1] [2]. The medical examiner said Sicknick suffered strokes the day after the Jan. 6, 2021 Capitol breach, noted there were no internal or external injuries or evidence of an allergic reaction to chemical irritants, and described the manner of death as natural [3] [4] [5].

1. Medical finding and the precise medical language

The medical examiner’s autopsy report attributed Sicknick’s death to "acute brainstem and cerebellar infarcts due to acute basilar artery thrombosis," a description that medical reporters summarized as strokes caused by blockages in arteries supplying the brainstem and cerebellum [1] [5]. Multiple outlets reported that the Office of the Chief Medical Examiner, led by Dr. Francisco J. Diaz, listed the manner of death as "natural," meaning the office concluded disease alone caused death rather than an external injury or intentional act [6] [4].

2. Timeline the examiner provided and the release date

The medical examiner’s statement recounted that Sicknick was sprayed with a chemical substance outside the U.S. Capitol on January 6, collapsed that night around 10 p.m., was transported to a hospital, and died the following evening; the ruling announcing cause and manner of death was released and widely reported on April 19, 2021 [5] [7] [2]. The U.S. Capitol Police issued a press release the same day accepting the medical examiner’s findings [2].

3. What the examiner said about injuries and chemical exposure

Dr. Diaz and the medical examiner’s office stated the autopsy found no evidence that Sicknick suffered an allergic reaction to chemical irritants and reported no internal or external injuries that caused his death [4] [8]. Though prosecutors had charged two men with spraying Sicknick during the riot, the office’s public ruling specified that chemical exposure was not found to have caused the fatal strokes [3] [9].

4. How the ruling affected criminal-investigation prospects and public narratives

The natural-cause determination was widely reported as diminishing the prospects for homicide charges directly tied to Sicknick’s death because prosecutors would have to show the assault caused the fatal medical event; news organizations framed the ruling as a likely impediment to murder prosecutions in his death [1] [10]. Still, law-enforcement officials, including the U.S. Capitol Police, maintained that Sicknick died in the line of duty and emphasized the broader criminal investigations into assaults on officers during the Jan. 6 breach [2] [11].

5. Remaining questions, alternative readings, and limits of the public record

The medical examiner also commented that the events of Jan. 6 "played a role in his condition," language some outlets noted as tension between ruling death "natural" and acknowledging situational contribution, but the public record released did not provide detailed explanation of preexisting conditions or how stressors might physiologically precipitate basilar artery thrombosis, in part due to privacy limits cited by the examiner [4] [12]. Reporting shows both the examiner’s specific pathological conclusion and the contemporaneous uncertainty in investigative and prosecutorial channels; given the sources provided, there is no public autopsy addendum here that quantifies how much the Jan. 6 confrontations contributed mechanistically beyond the examiner’s statement [4] [3].

Want to dive deeper?
What evidence did prosecutors present when charging suspects in assaults on officers during the Jan. 6 Capitol riot?
How do medical examiners determine when an acute stroke is caused or precipitated by external events or stressors?
What has subsequent reporting revealed about preexisting conditions or additional medical details in Brian Sicknick’s death?