Gene Hackman, his wife Betsy Arakawa, and their dog’s mysterious deaths have authorities searching for answers … and they’ve confirmed they’re not ruling out carbon monoxide poisoning.

Santa Fe fire officials spoke on “TODAY” Friday, stating that while their meters didn’t detect anything amiss during searches, that doesn’t mean carbon monoxide poisoning is off the table — especially since the bodies may have been there for days or even weeks.

They pointed out Gene and Betsy’s New Mexico home had natural gas … and a leak could have dissipated by the time their bodies were discovered.

Authorities also aren’t entirely ruling out foul play, even with little evidence to support it. They say the toxicology report — which could take up to 3 months — will be key in determining the causes of their deaths and guiding their investigation.

But as for carbon monoxide poisoning, Gene’s family strongly believes it’s the cause.