DENVER -- Detectives in Pitkin County said they are focusing their investigation into the death of a family of four on whether or not the house had a carbon monoxide detector.

Pitkin County building code requires homes to have one detector, but the law does not specify where the detector should be in the house.

Investigators said Tuesday they have not yet determined if the house was in compliance.

A team of technicians determined the house's hot water and snow melting systems malfunctioned. This caused the extreme levels of carbon monoxide in the house.

Sheriffs deputies said the family from Denver died Friday of carbon monoxide poisoning. The coroner ruled the deaths as accidental.

The victims were found in a bedroom two floors above the crawlspace which houses the mechanical equipment.

The home is owned Black Diamond Land Development Corp., Denver, according to the Pitkin County Assessor's Office and was recently built. The registered agent is Jonathan M. Thomas, according to the Colorado Secretary of State's Office.

The Lofgren children were enrolled at St. Anne's Episcopal Church and School. A prayer service for the family was held at the school Monday morning and attendance at the school was optional on Monday.

It is the second family tragedy affecting St. Anne's school in the last four months. In August, students Sam and Grace Masoudi were killed when a plane crashed into the vacation home their parents were renting in Gearhart, Ore. Their cousin, Julia Reimann, also died in addition to two people in the plane: Jason Ketchson and Frank Toohey, of Oregon.

Carbon monoxide is the leading cause of accidental poisoning deaths in North America.