A district judge has decided there is probable cause for negligent-homicide charges against a subcontractor and former building inspector in connection with the carbon-monoxide poisoning deaths of a Denver family of four in 2008. Chief Deputy District Attorney Arnold Mordkin said Monday that District Court Judge James Boyd ruled there is probable cause to proceed with a pretrial hearing beginning Nov. 28 against Marlin Brown, 57, and Erik Peltonen, 69, after a Pitkin County grand jury indicted Brown and Peltonen on four negligent-homicide charges. The two entered pleas of not guilty."The pipes vented the carbon monoxide exhaust, instead of outside through the pipes, the pipes were broken, and it vented it inside the house," Mordkin told 7NEWS.Brown is the owner of Roaring Fork Plumbing and Heating, which installed the boiler and pipes at the home, Mordkin said. Peltonen, who is now retired, was the city of Aspen building inspector for the home. Details of the case have been kept under seal in court records.Misdemeanor charges against a third man, Pitkin County building inspector Brian Pawl, were dropped after prosecutors realized the statute of limitations on the misdemeanors had expired. The charges were a result of the fatalities of Caroline Lofgren, her husband, Parker, and their two children, Owen, 10, and Sophie, 8. The Lofgrens bought a weekend stay at the luxury home in Aspen at a church auction.Friends joining them for the holiday weekend found the family of four dead from the deadly gas leak in the home.