Le Mesurier, 48, was a former British army officer who founded the volunteer first responder group.
His body was discovered near his home on Monday by worshippers who were on their way to a mosque close by, Anadolu reported at the time.
No one had been seen entering or exiting the building at that time. When police interviewed Winberg, she told them that her husband had been taking sleeping pills and other medication because of "extreme stress."
She said they had been awake until about 4 am and then both of them took sleeping pills. She was awoken by the doorbell about 1.5-2 hours later and saw his body on the ground from their apartment on the third floor, Anadolu added, citing police.
They had moved to Turkey four years back, the wife added.
The White Helmets - also known as the Syria Civil Defence - has some 3,000 members and was formed in 2014.
The group is made up of volunteers who work in rebel-held areas in Syria, helping rescue survivors from bombed-out buildings, fight fires and offer first aid.
Le Mesurier's remains were sent to London on Wednesday.
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