The investigation into the mysterious deaths of actor Gene Hackman and his wife, Betsy Arakawa, at their home in Santa Fe, New Mexico, entered its third day Friday with more looming questions than answers.

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.

The bodies of Gene Hackman and his wife, Betsy Arakawa, both tested negative for carbon monoxide poisoning. Hackman's pacemaker stopped Feb. 17.