The African rock python that escaped its enclosure and is believed to have killed two New Brunswick boys may have been lured by the scent of the children because they were playing with farm animals hours earlier and may have smelled like prey, one reptile expert said Tuesday.

The founder and co-owner of Little Ray's Reptile Zoo in Ottawa said snakes such as the one that police believe killed Noah and Connor Barthe don't visually recognize their prey, so if the boys smelled like the animals they were playing with, it could serve as an explanation for the attack.

"If a snake sees an animal moving, giving off heat and smells like a goat, what is it? It's a goat," said Paul (Little Ray) Goulet.

"This is the reasonable explanation of how this has happened is that they had been playing with farm animals, they did smell like their prey items and the snake sadly enough mistook them as a food item when they weren't."

Dave Rose, the great uncle of the boys, said the four- and six-year-old boys spent Sunday playing at Jean-Claude Savoie's family farm.

"There they played with lamas and goats and horses, they played with dogs and cats in the hayloft, went for a ride on the farm tractor with Jean-Claude and he even let them steer the tractor," Rose said.

Savoie later took Noah and Connor to his apartment in Campbellton, N.B., where, police say, the 45-kilogram snake escaped its floor-to-ceiling glass tank and slithered through a ventilation system before its weight forced it to fall through the ceiling into the living room where the boys slept Sunday night. Their bodies were found Monday morning and the snake has since been put down.

Goulet said snakes have become adept at sensing prey through scent and if they're hungry, they will strike.

"If you were to take a chicken or a rabbit and you rub it all over your hands and your arm, and you stick your hand in front of that animal's face and it's hungry, it will immediately grab your arm and wrap around you," he said.

"They are ambush predators. Millions of years of evolution has taught them that food just doesn't flop in front of your face every day."

Other reptile experts agreed that it is extremely rare for African rock pythons to kill humans.

"It'd be like getting struck by lightning twice in one day," said Matt Korhonen, general curator at Little Ray's Reptile Zoo.

"The fact that this snake escaped ... and killed two kids is very much a freak accident."

Korhonen, who has worked at the zoo since 2000, said rock pythons are not known for killing humans, though they are an aggressive species of serpent that can grow to be very large and powerful.

"That doesn't mean that they attack and kill people," he said. "It's just that they're very nervous."

The Mounties said Monday they believed the 4.3-metre long python strangled the boys but on Tuesday investigators said they are waiting for the results of an autopsy on the children as well as a necropsy on the snake before commenting further on the cause of death.

James Bogart, a retired professor and reptile specialist at the University of Guelph in Ontario, said it doesn't make sense to him that the snake would strangle the two boys and then leave their bodies alone.

"They're not malicious creatures -- they go after things for food," Bogart said.

"It just doesn't make sense to me that it would actually strangle two boys and leave them. I'm not sure why it would kill one and then kill the other one. It really doesn't make sense."

Korhonen said if the snake constricted the boys, it was doing so not out of self-defence but rather out of hunger.

"If they were constricted and killed by the snake, they were seen as prey," he said. "The snake wasn't defending himself. He was trying to eat."

Korhonen said thousands of rock pythons are kept in people's homes as pets across North America and they don't attack. Still, he warned that the animals shouldn't be kept as pets, given their size and potential to kill.

"Having any animal that's capable of killing you in your home is probably just not a good idea," Korhonen said.

"Giant snakes -- I would never say that that's a good idea."