British co-founder of Syria White Helmets 'died from fall'
He was found dead on November 11 outside the Istanbul apartment building where he lived.
The autopsy report said he died due to "general body trauma linked to a fall from height", state broadcaster TRT Haber said.
No DNA belonging to another person was found.
The four-page report from the Forensic Medicine Institute said Le Mesurier suffered internal bleeding and broken bones, the private DHA news agency added.
Turkish police are believed to be treating the death as suicide.
Local media has claimed he sought help for mental health issues and his wife, Emma Hedvig Christina Winberg, reportedly told police he had had suicidal thoughts two weeks before his death.
Read more: Mourning the loss of a true humanitarian: Ally of Syria's White Helmets, James Le Mesurier
Authorities barred his wife from leaving Turkey until the investigation has been completed, Turkish agency DHA reported last month.
The couple's domestic worker, who was in the building at the time, has told police she knew nothing about how Le Mesurier died, according to DHA.
Le Mesurier's body was repatriated to the UK in November.
The former army officer was widely labelled as the founder of the White Helmets, the rescue organisation responsible for saving hundreds of civilians from the rubble of Syrian regime and Russian airstrikes.
Le Mesurier rejected the label, insisting in a 2016 interview with The National that efforts to present the group as having a foreign founder were "an effort to undermine the credibility of the Syria Civil Defense".
In the aftermath of his death, a top Russian official had alleged Le Mesurier was a spy - a claim Britain strongly denies.
Following his death, activists on social media have suggested the involvement of Russia's intelligence agency, the Federal Security Service (FSB).