ASPEN, Colo. -- The deaths of a Denver family of four appears to have been caused by a disconnected plastic exhaust pipe connected to a boiler in the Aspen-area home they were staying at over the Thanksgiving holiday.

Pitkin County Sheriff Bob Braudis told reporters Tuesday that the PVC pipe was not connected at an elbow joint, allowing carbon monoxide from the boiler to leaking into the home.

The pipe was part of the snowmelt system used to keep ice from collecting on the driveway of the 3,250-square-foot home at 10 Popcorn Lane home, 4 miles east of Aspen.

The bodies of Parker Lofgren, 39, his wife Caroline, 42, and their children, Owen, 10, and Sophie, 8, were found, on Nov. 28, in the nearly $9-million estate by another family that arrived to share the home over the holidays.

Autopsies determined the four died of carbon monoxide poisoning.

What still isn't clear is if the home was equipped with a carbon monoxide detector. The county building code requires a CO detector in every house built.

The home is owned Black Diamond Land Development Corp., Denver, according to the Pitkin County Assessor's Office and was recently built.

The two families had won a silent auction for the right to spend the Thanksgiving holiday in the home.