The wife of White Helmets founder James Le Mesurier, who was found dead near his home in Istanbul on Monday, has been barred from leaving the country pending the investigation into Le Mesurier's death.

The travel ban on Emma Hedvig Christina Winberg, 38, who previously gave testimony twice, was imposed yesterday as part of the investigation into Le Mesurier’s death.

Le Mesurier was the founder and CEO of May Day Rescue, which established and trained the White Helmets, also known as the Syria Civil Defense, a group of local humanitarian volunteers. Anadolu Agency (AA) reported he was 48 and had moved to Turkey with his wife four years ago. The White Helmets have been credited with saving thousands of people in opposition-held areas during years of bombing by the Bashar Assad regime and Russian forces in the Syrian civil war.

While an investigation into his death continues, it was revealed that a Syrian boy who sold tissues in front of Le Mesurier’s house disappeared a while ago. Speaking about the tissue seller, Yavuz Aydın, a shopkeeper living in the area, said that the Syrian boy had been there for one year intermittently. "I heard that he is selling tissues in different places of Karaköy district. He was here one month ago, then he disappeared," Aydın said.

Shopkeepers said that the name of the Syrian boy was Mohammed, and was identified as fair with colored eyes and a stubble who reportedly fled from the Syrian war a year ago. "When I asked him whether he was working for Syrian intelligence, he refused and answered that his village was bombed so he fled," Aydın said.