My GUESS will be a heart attack. The Criminal Complaint lays out a confusing mish-mash of reasons: "The Hennepin County Medical Examiner (ME) conducted Mr. Floyd's autopsy on May 26, 2020. The full report of the ME is pending but the ME has made the following preliminary findings. The autopsy revealed no physical findings that support a diagnosis of traumatic asphyxia or strangulation. Mr. Floyd had underlying health conditions including coronary artery disease and hypertensive heart disease.
The combined effects of Mr. Floyd being restrained by the police, his underlying health conditions and any potential intoxicants in his system likely contributed to his death. The tox screen has not been released and neither has the full ME report.
https://www.abc57.com/news/read-the-criminal-complaint-against-ex-minneapolis-police-officer-derek-chauvin