PARKS, Ariz. - Investigators suspect the family of four found dead in a Parks cabin Monday afternoon may have died from accidental carbon monoxide poisoning.

A heating specialist arrived at the 1830 N. Lance Drive Tuesday at approximately 11 a.m. and was seen walking into the cabin with authorities.

Later Tuesday, the Coconino County Sheriff's Office said the contractor found a "significant failure" in the cabin's heating system, which is additional evidence of possible carbon monoxide poisoning. The Coconino County Medical Examiner's Office will determine an official cause of death.

The cabin, owned by a family friend, is equipped with a gas furnace, said Coconino County Sheriff's Office spokesman Jon Paxton.

“We investigate everything like it's a crime,” said Paxton. “Right now we are leaning towards accidental carbon monoxide poisoning but we will leave the final decision to the medical examiner's office.”

Carbon monoxide poisoning is known as the “silent killer” because it is odorless and colorless, according to the CDC.

Ponderosa Fire Chief Lee Antonides says sometimes it is possible to smell a leak from a propane gas furnace.

“It depends on how strong the smell is, how rich and when the furnace was last serviced," he said. “Sometimes you can smell it and sometimes you can't."

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Antonides also strongly recommended having a certified heating specialist check your unit before lighting up for the winter.

“It's important to, if you're renting a place you're not familiar with, to ask when the last time the furnace was inspected,” said Paxton. “Ask if there's a carbon monoxide detector in the house and if there is, make sure it functions.”

The family -- Anthony Capitano and his wife Megan Capitano, both 32, 4-year-old Lincoln and 3-year-old Kingsli, of El Mirage -- traveled to the cabin on Friday night, Paxton said.

“It is my understanding that the family came up late Friday night,” he said. “We believe this may have happened sometime early Saturday morning.”

On Monday morning, a friend of the family called law enforcement to request a welfare check after they were unable to reach them.

A deputy responded to the cabin and upon seeing the family car in the driveway, did a property check, said Paxton.

The deputy noticed a “strong odor” and requested additional units.

The Ponderosa Fire Department responded to the scene at approximately 1:45 p.m. with protective breathing equipment and found the family in the home.

The Coconino County Sheriff's Office is still investigating and the official cause of death for the family has yet to be released.