The British founder of an organization that trained the Syrian White Helmets emergency response group died in İstanbul on Monday, the Middle East Eye (MEE) news website reported, citing sources.

James Le Mesurier, founder of the Mayday Rescue group, was found dead early on Monday in central İstanbul’s Beyoğlu district, a Turkish source with knowledge of the case told MEE.

“He appeared to have fallen from a height. Current information suggests he had committed suicide,” the source said on condition of anonymity.

A second Turkish source with knowledge of the case told MEE that the building was only accessible by using fingerprint identification.

Preliminary evidence suggests that the system was only accessed by Mesurier and his wife overnight.

“Mesurier and his wife appeared to have been alone in the building at the time of the death,” the source said.

A security source told Reuters: “Le Mesurier’s wife told police that she and her husband had taken sleeping pills around 4 a.m. and went to bed.

“She said she was later woken by knocking on the door and discovered that her husband was lying on the street surrounded by police,” the source added.

Meanwhile, another source told the privately owned Turkish Demiören news agency that police had found his face had been cut by a sharp object.

In an official statement, the İstanbul Governor’s Office said “a comprehensive administrative and criminal investigation on the death of English citizen James Gustaf Edward Le Mesurier” had been opened.

Last week Russian foreign ministry spokesperson Maria Zakharova accused Mesurier of being a “former agent” to the United Kingdom MI6 intelligence agency and said he had connections to “terrorist groups.”

The White Helmets, known officially as Syria Civil Defense, have been credited with saving thousands of people in rebel-held areas during years of bombing by Syrian government forces and its ally Russia in the country’s civil war.