Gene Hackman and his wife, Betsy Arakawa, tested negative for carbon monoxide poisoning, the Santa Fe Sheriffs Department in New Mexico said Friday, one day after they were found dead with their dog.

Hackman and his wife, Betsy Arakawa, apparently had been dead for days or even a couple of weeks when investigators found their bodies while searching the couple’s Santa Fe home on Wednesday. Investigators are trying to figure out the last time anyone saw or spoke to them, Santa Fe County Sheriff Adan Mendoza told NBC’s “Today” show on Friday.

Arakawa “hadn’t called” her 91-year-old mother, Yoshie Feaster, who suffers from dementia, since October, according to the elder’s housekeeper, Keiko. Keiko spoke to Daily Mail on Friday, just two days after Hackman, 95, and Arakawa, 65, were found dead in their Santa Fe, New Mexico, home, along with a deceased dog.