How did Mahsa Amini die?

The CCTV video documenting Amini from her arrival at the detention center up until her collapse depicts no violence and no indications of prior violence. Amini and everyone who exits the police van with her seems calm and acts normally. 

As such, this evidence is extremely unlikely under the Murder hypothesis, somewhat unlikely under the Involuntary Manslaughter hypothesis, and to be expected under the Natural Causes hypothesis. 

There have been three main sources claiming to provide medical evidence or a diagnosis as to the cause of Amini's death: leaked medical tests that appeared in the media, pictures of Amini in the hospital, and an official diagnosis by Iran’s coroner.

We disregard these claimed tests as they are uncorroborated and originate from an unreliable source. Amini’s hospital pictures and the coroner report show no indication of violence and as such, reduce the likelihood of the Murder and Involuntary Manslaughter hypotheses.

Testimonies appearing in the media have mostly described Amini being beaten by the police, which supports the Murder and Involuntary Manslaughter Hypotheses. However, this effect is reduced as all of these testimonies are uncorroborated, hearsay testimonies, mediated either by media organizations funded by countries aiming for regime change in Iran or by Amini’s family, who are more likely to provide such information whether true or false. At least part of Amini’s family also has a significant bias against Iran’s government and is active in a political and armed conflict against it, with the hope that "these protests will continue and it will end with the fall of the Islamic Republic". On top of this, some testimonies contain internal contradictions while others are contradicted by the CCTV footage. 

A few of the testimonies do carry more significant weight: Amini’s father claimed she did not have brain surgery (contrary to official claims) and that he saw blood on her body. These claims further support the Murder and Involuntary Manslaughter hypotheses while one testimony significantly supports the Natural Causes hypothesis: Amini’s brother received the diagnosis that his sister suffered a stroke and a heart attack within 17 minutes of her collapse. This is unlikely to be sufficient time to establish a conspiracy to hide her true cause of death and thus was likely a truthful diagnosis.