Gene Hackman's Friend Has 'No Idea' What Could've Caused His, Wife Betsy's Deaths: 'More Mysterious All the Time' (Exclusive)

Gene Hackman and his wife Betsy Arakawa's deaths took even their friends by surprise.

Days after the legendary actor, 95, and his wife, 65, and their dog were found dead in their New Mexico home on Wednesday, Feb. 26, details about their death remain unclear — especially for those who were close to them.

At a press conference on Friday, Feb. 28, the Santa Fe County Sheriff's Department said Hackman's pacemaker was last operational on Feb. 17, suggesting that Hackman had been dead for nine days before he and his wife's bodies were found.

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According to a search-warrant affidavit reviewed by PEOPLE, Arakawa was found in the bathroom, next to a space heater and an open bottle of pills. The pills included an unspecified thyroid medication, Tylenol, and diltiazem, a medication used to treat high blood pressure. Two dogs who were alive were also found at the home.

Family friend Barbara Lenihan tells PEOPLE that "Betsy was in perfect health" and "she was so fit."

"Gene was 95, and for all I know it was prescription medicine. We do not know what happened. I know the media's making a bunch out of it, but we have no idea," says Lenihan. "I don't know if it was carbon monoxide. They say no, but the door was open and they could have been there for a couple weeks."

During Friday's press conference, police said the couple tested negative for carbon monoxide, causing it to be ruled out as the cause of the couple's deaths. They said authorities are still awaiting autopsy and toxicology results.

Police said Arakawa's body showed signs of "mummification,"  leading to the belief that she had likely been dead for some time. Hackman's body also showed similar "obvious signs of death."

Lenihan tells people that she and her husband, Daniel understood Hackman was "getting quite old," making them try to "prepare ourselves for Gene's [departure] but we are just stunned. We're stunned about Betsy."

She says that their death is "more mysterious all the time."

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"We don't have any answers, and we're just dealing with the loss," she adds.