TORONTO (AP) — The mother of two small boys strangled by a 100-pound (45-kilogram) python in their sleep earlier this week in Canada had posted photos on Facebook last year of the boys playing in and cleaning her neighbour’s snake enclosure.

Mandy Trecartin’s Facebook page has hundreds of photos of her sons, including a few showing Noah Barthe, 4, and Connor Barthe, 6, happily scrubbing the glass enclosure, which she identified as an anaconda habitat. It was not clear whether the enclosure is the one that held the python.

Preliminary results from autopsies performed on the boys show they died from asphyxiation, officials said Wednesday. Hundreds of people in the shocked community of Campbellton, New Brunswick, gathered for a candlelight vigil Wednesday evening in a show of support for the family.

The snake, an African rock python, apparently escaped from its enclosure, slithered through a ventilation system and fell through the ceiling into the room where the young boys were sleeping, authorities said. They had been visiting the apartment of a friend whose father owned an exotic pet store on the floor below.

A snake expert said it was possible that the python was spooked and simply clung to whatever it landed on.

Authorities on Wednesday planned to remove other animals from the pet shop, though Royal Canadian Mounted Police Sgt Alain Tremblay said the 4.3-metre (14-foot) python had been kept inside the apartment. Police are treating the deaths in Campbellton, New Brunswick, as a criminal investigation.

Tremblay said the snake was housed in a large glass enclosure that reached the ceiling of the apartment and escaped through a small hole in the ceiling connected to the ventilation system. He said the snake made its way through the ventilation system, the pipe collapsed and the snake fell.

The friend of the boys was sleeping in another room and was unharmed.

The pet-store owner, Jean-Claude Savoie, has told a television station that he didn’t hear a sound and discovered the “horrific scene” when he went into his living room on Monday morning.

Police said the snake was killed by a veterinarian. It was sent for a necropsy to confirm the type of snake and help understand what may have caused it to attack.

Mark Johnson, a spokesman for Environment Canada, said the snake was abandoned at a local SPCA in 2002 and federal wildlife officials assisted with relocating the python to the pet store.

Anne Bull, a spokeswoman for the New Brunswick’s Natural Resources department, said the African rock python is no longer permitted in the province and said the department had no knowledge of the existence of the snake prior to this week’s tragedy. The African rock python has been illegal in the province since 2009.

Bull said the department has obtained a search warrant for the store and said a number of exotic animals were discovered while police were investigating.

“If we discover any illegal exotic animals, they will be seized and efforts will be made to relocate them to accredited zoos,” Bull said in an emailed statement.

Paul Goulet, founder and co-owner of Little Ray’s Reptile Zoo in Ottawa, said snakes don’t recognize humans as a source of food, but if the children smelled like animals, it could explain an attack.

“If a snake sees an animal moving, giving off heat and smells like a goat, what is it? It’s a goat,” Goulet said.