The last days of Gene Hackman and wife Betsy Arakawa: A timeline

More details -- including an altered timeline -- are emerging as officials continue to investigate the tragic deaths of actor Gene Hackman and his wife, Betsy Arakawa, who were both found dead in their Santa Fe, New Mexico, home in February.

"Last Days of Gene Hackman: ABC News Special" airs Tuesday, March 18, at 10 p.m. ET on ABC.

Here's the timeline of the case:

Feb. 9

On Feb. 9, Arakawa picked up one of their three dogs -- the dog who was later found dead in the home with the couple -- from a veterinary hospital after a procedure, which may explain why the dog was discovered in a crate when the bodies were found, Santa Fe County Sheriff Adan Mendoza said.

Feb. 11

On the afternoon of Feb. 11, Arakawa went to a farmer's market, CVS and a pet food store, and entered her gated community at 5:15 p.m., the sheriff said.

Authorities initially believed the 65-year-old Arakawa died on Feb. 11.

Feb. 12

Investigators later discovered that on the morning of Feb. 12, Arakawa called concierge medical service Cloudberry Health three times, the sheriff said.

"Each time that she called, she individually spoke to a representative," Mendoza told ABC News. "That would indicate to me that she was seeking medical advice or medical help, and may have not been feeling well or had been showing signs or feeling symptoms of hantavirus."

Arakawa wasn't a patient but called about an "esoteric treatment," according to Dr. Josiah Child of Cloudberry Health.

There was no sign that she had any sort of "breathing issue ... or that she was in any way in distress or that this was an emergency," Child said.

Cloudberry Health called Arakawa back twice to follow up, but never got a response, Child said.

Though the exact date of Arakawa's death is not clear, authorities said she died from hantavirus pulmonary syndrome, a rare disease transmitted through rodent urine, droppings or saliva.

Those who contract hantavirus often feel ill for roughly three to six days, according to Dr. Heather Jarrell, chief medical investigator for the state's Office of the Medical Investigator.

"Then they can transition to that pulmonary phase, where they have fluid in their lungs and around their lungs," Jarrell said. "And at that point, a person can die very quickly, within 24 to 48 hours, roughly speaking, without medical treatment."

Feb. 18

Hackman, 95, likely died around Feb. 18, about one week after his wife, officials said.

The Academy Award-winning actor's death was from cardiovascular disease with "Alzheimer's disease as a significant contributory factor," Jarrell said.

Hackman's "initial pacemaker data revealed cardiac activity on Feb. 17, with subsequent pacemaker interrogation demonstrating an abnormal rhythm of atrial fibrillation on Feb. 18, which was the last record of heart activity," Jarrell said.

Hackman was likely home with his deceased wife for about one week before he died, the sheriff said.

He "was in an advanced state of Alzheimer's, and it's quite possible that he was not aware that she was deceased," Jarrell told reporters, adding that the "question is difficult to answer."

Feb. 26

On Feb. 26, the couple's bodies were discovered during a welfare check, the sheriff's office said.

Hackman was on the floor in the mud room while Arakawa was on the floor in a bathroom with a space heater near her body, according to the search warrant.

Arakawa's body showed signs of decomposition; there was mummification to her hands and feet, the document said.

One of the couple's three dogs was found dead in a crate about 10 to 15 feet from Arakawa's body, officials said. The dog likely died of dehydration and starvation, according to a necropsy report.

The couple's two other dogs were found alive. It appeared they had access to a doggy door; one dog was found near Arakawa's body and the other was located outside, the sheriff said.

Hackman is survived by his son and two daughters.

Hackman "was loved and admired by millions around the world for his brilliant acting career, but to us he was always just Dad and Grandpa," his daughters and granddaughter said in a statement. "We will miss him sorely and are devastated by the loss."

What happens to Hackman's estate?

Hackman left his $80 million estate to his wife and did not name his children. Arakawa left her estate to charity.

The timeline of their deaths could play a factor in the couple's wills.

"If Betsy passes away first, and then Gene, his will, in a sense, would become void, because the individual he wanted his items to be passed to no longer exists in the eyes of the law," ABC News legal contributor Brian Buckmire said.

"His estate and everything he left in his will would go to probate court, where individuals can argue that they should receive the benefits of Gene Hackman's will," Buckmire said.

Hackman's son has hired a California trust and estate attorney.

ABC News' Muriel Pearson, Eileen Murphy and Eric Strauss contributed to this report.