Gene Hackman 's pacemaker was last operational on Feb. 17, the Santa Fe County Sheriff said Friday afternoon, suggesting the Oscar-winning actor had been dead for nine days before he and his wife, Betsy Arakawa, were discovered in their New Mexico home.

Authorities said there were no obvious signs of foul play but the circumstances of their deaths warranted further investigation.

Santa Fe County Sheriff Adan Mendoza told NBC's “Today” show that investigators were trying to sort out conflicting stories about the doors. He said several doors were unlocked and a rear door was open, which allowed two dogs that survived to go in and out. He also said he thinks the front door was closed but unlocked.