Oscar-winning actor Gene Hackman’s pacemaker shows he probably died on Feb. 17, days before investigators found his body and that of his wife in their New Mexico home.

At a news conference, Santa Fe County Sheriff Adan Mendoza said the initial examination by the medical examiner showed no sign of carbon monoxide, a colorless and odorless gas produced from kitchen appliances and other fuel-burning items. When it collects in poorly ventilated homes, it can be fatal.

US investigators are trying to establish how Oscar-winning actor Gene Hackman and his wife, classical pianist Betsy Arakawa, died after the discovery of their bodies at their home in the US state of New Mexico.