A forensic expert commented on the investigation and based on his experience what may have happened:
As new details begin to unravel, Dr. Michael Baden, chief forensic pathologist for the New York State Police Department, delivered his new theory to DailyMail.com.
'This is a sad situation all around,' he said.
Given the new findings, Dr. Baden believes that the retired star may have suffered from a sudden cardiac arrhythmia episode - a malfunction of the heart's electrical system that occurs when the signals telling the heart to beat don't work properly.
This could have led to Gene's fall, which would align with how his body was discovered - in the mudroom off the kitchen, with his sunglasses and cane sprawled out on the floor.
'If the pacemaker stops functioning properly, it is easier for a sudden cardiac arrhythmia to happen,' Dr. Baden told DailyMail.com.
'It sounds like he died from a fatal arrhythmia, and the autopsy will determine if heart disease was a factor.'
Given that carbon monoxide has been ruled out, Dr. Baden believes that Betsy most likely would have panicked upon discovering her husband on the floor and hurriedly ran to the bathroom to grab his medication.
Betsy's body was discovered decomposed on that bathroom floor,
with a prescription bottle of pills open and its contents strewn across the counter.
Police reported finding the over-the-counter pain reliever Tylenol, an unspecified thyroid medication and diltiazem - commonly used to treat high blood pressure and certain heart conditions.
It is not clear yet whether Betsy had taken the medicines found in the bathroom or if Gene had - or whose name was printed on the canister.
Dr. Baden had previously suggested a good question to ask officers was whether they had opened any doors or windows for a long period of time during their investigation.
'What happens when police come into a decomposing cause, they get upset of the bad odor and they are concerned they will catch something because it is distasteful, the smell,' he told DailyMail.com.
'It's a lousy odor and the first thing they sometimes do is open the windows to let the bad odor out. That could affect the net negative reading at the scene.'
Initially, Dr. Baden believed that the carbon monoxide theory was the only one that made sense.
'Even if they died of a natural disease, people don't flop on the floor like that, the way their bodies were found,' he said. 'They usually lie down on the bed and call a doctor.'
Forensic expert: Gene Hackman may have suffered a heart malfunction