Gene Hackman's wife Betsy Arakawa was still alive a full day after authorities initially believed she had died, according to newly uncovered phone records

The revelation by the Santa Fe Sheriff's Department contradicts earlier reports and adds a layer of mystery to the timeline surrounding her passing.

Authorities from the Santa Fe Sheriff's Department told Fox News: "We can now confirm that Mrs Hackman's phone was utilised on the morning of 12 February to call a medical centre in Santa Fe, Cloudberry Health.

"A total of three calls were made that morning, all to the medical centre. One incoming call was made to Mrs Hackman from the same medical centre that afternoon. That appeared as a missed call on Mrs Hackman's cell phone."

The finding supports claims made by Dr Josiah Child, a former emergency care specialist who runs Cloudberry Health.

Dr Child, who had spoken to Betsy a few weeks prior to her death, previously stated she had scheduled an appointment for 12 February.

He said: "She made an appointment for herself for 12 February. It was for something unrelated to anything respiratory."

He noted Betsy later cancelled the appointment, citing concern for her husband's deteriorating health.

Betsy had been diagnosed with hantavirus pulmonary syndrome, a rare and potentially deadly disease transmitted through rodent exposure.

But Dr Child questioned whether her condition was as severe as reported.

He added: "It is surprising that Mrs Hackman spoke to my office on the phone on 10 February and again on 12 February and didn't appear in respiratory distress.

"Most patients who have hantavirus die in hospital."

Adding to the uncertainty, Gene, 95, who suffered from advanced Alzheimer's, was reportedly alone in the couple's home for days following Betsy's death.

Authorities later confirmed he passed away on 18 February, a week after his wife.

His cause of death was ruled as hypertensive atherosclerotic cardiovascular disease, with Alzheimer's playing a significant role.

Neither Gene or Betsy's bodies were discovered until 26 February, when a neighbour's caretaker called 911 after finding them unresponsive.

The discovery of Betsy's phone activity on 12 February raises further questions about the timeline and circumstances of her death.

Meanwhile, Gene's $80million estate could now be inherited by his three children - Christopher, 65, Elizabeth, 62, and 58-year-old Leslie - despite none being named in his will.

Legal experts say Gene's will, last updated in 2005, named only Betsy as the beneficiary.

With her death preceding his, the estate may now be subject to intestate succession laws.

California attorney Tre Lovell told the BBC: "The estate will actually be probated in accordance with intestate succession laws and the children would be lawfully next in line to inherit."

However, Gene's children would likely need to provide legal evidence their father's will is invalid due to Arakawa's earlier death.