Dave Walker spoke the language, knew the streets and was familiar with the local culture.
Walker, who had been living in Cambodia for the past year and a half, was staying at a guest house last week when he decided to step out while a housekeeper tended to his room.
He apparently left his room Friday afternoon with only a bottle of water and never returned.
"This is completely out of character for him," Walker's cousin, Tammy Wallbridge Madon told The Canadian Press. "All indications were that he was going to be coming back and he never did come back."
Walker's disappearance was first noticed by his Cambodian business partner, Sonny Chhoun, who came to the guesthouse on Friday evening to meet with him.
Chhoun found Walker's cellphone, laptop, luggage and passport still in his room, but staff at the guest house said they hadn't seen the Canadian in hours.
After Walker failed to turn up that night, Chhoun contacted local police and has been searching parts of the city looking for the Canadian, who hasn't been heard from since.
A local media report said the Australian embassy — which handles consular cases in Cambodia for the Canadian government — had filed an official missing persons report on Walker in the capital city of Phnom Penh.
The Phnom Penh Post quoted a police officer saying authorities were worried for Walker's safety and were searching for him.
Walker and Chhoun had set up a film company in Siem Reap in July 2012 called Animist Farm Films. Siem Reap is located just south of the famous Angkor Wat ruins, which draw hordes of tourist every year.
The pair had recently been working on a documentary about the radical Khmer Rouge regime, which left close to two million people dead from starvation, medical neglect, slave-like working conditions and execution.
Walker's abrupt disappearance had his friends and family fearing the worst.
"This is very unusual," said Peter Vronsky, who last heard from Walker on Thursday. "No one has seen him on the streets."
Vronsky said missing person posters were being distributed in Siem Reap in the hopes that someone would come forward with information on Walker.
Friends and family are also hoping Canadian officials will urge Cambodian authorities to actively search for the man.
"We're concerned this not being made a priority," said Vronsky.
Walker grew up in Edmonton but last lived in Toronto, where he studied for a Masters degree at York University in 2009. His family said he has lived and worked in Southeast Asia on and off for years.
He also co-authored a non-fiction book, called "Hello My Big Big Honey," which chronicles the experiences of Bangkok bar girls and their Western admirers.