Chief Deputy District Attorney Arnold Mordkin said last week that a grand jury was convened earlier this year in part to consider the deaths of Parker and Caroline Lofgren of Denver and their two children, ages 8 and 10.

The Lofgrens were found dead the day after last Thanksgiving in an Aspen-area home where they were spending the holiday.

Investigators said a disconnected exhaust pipe leaked the odorless gas into the house. The home didn't have a carbon monoxide detector even though a county ordinance required one.

A state law approved this year requires most new homes to install detectors.