New Mexico authorities say preliminary autopsy results didn't determine how Oscar-winner Gene Hackman and his wife died, but did rule out carbon monoxide.

Preliminary autopsy results ruled out carbon monoxide in the deaths of Oscar-winner Gene Hackman and his wife, New Mexico authorities said Friday, as investigators continued to pore over evidence found around the couple's partially mummified bodies.

Hackman, a Hollywood icon, won two Oscars during a storied career in which he played an array of heroes and villains in films including “The French Connection,” “Hoosiers” and “Superman” from the 1960s until his retirement in the early 2000s.

At a Friday news conference, Santa Fe County Sheriff Adan Mendoza said the initial examination by the medical examiner showed that Hackman and Arakawa both tested negative for carbon monoxide. The colorless and odorless gas produced from kitchen appliances and other fuel-burning items can be fatal in poorly ventilated homes. No gas leaks were discovered in or around the home.

Mendoza said Hackman's pacemaker last showed activity on Feb. 17, meaning the former actor may have died nine days before maintenance and security workers showed up at his home.

Dr. Philip Keen, the retired chief medical examiner in Maricopa County, Arizona, said it would be unlikely for a person who tests negative for carbon monoxide initially to later be found to have been poisoned by it.

He also said the moment when a pacemaker stops working could mark the point when a person dies, but not always.

The couple's bodies were decomposing, with mummification in Arakawa’s hands and feet, according to a search warrant affidavit. Hackman’s body showed similar signs. Hackman’s body was found in the home’s entryway and Arakawa’s was found in a bathroom.

It's not rare for a body to mummify, Keen said, adding that the rate of mummification depends on the amount of moisture in the air, along with factors like altitude and body type. Santa Fe is in the driest region of the U.S. at an elevation of nearly 7,200 feet (2,194 meters).

Keen said mummification “doesn’t tell you much” when trying to determine time of death.

The initial autopsy findings also “noted no external trauma to either individual,” Mendoza said.

Detectives wrote in a search warrant affidavit that investigators thought the deaths were “suspicious enough in nature to require a thorough search and investigation.”

A German shepherd was also found dead, while two other dogs were found healthy, Mendoza said.

Authorities who searched the home retrieved medication that treats high blood pressure and chest pain, thyroid medication, Tylenol, and records from medical diagnostics testing, court records filed Friday showed.

Whether the pills or other drugs were a factor won’t be known until toxicology tests are completed in the coming weeks. Mendoza declined to say who the medication bottles were prescribed to, citing privacy concerns.

Authorities also retrieved two cellphones and a monthly planner. Investigators plan to comb through the phones' data to analyze their calls, text messages, photos and events.

The couple was a “very private family,” Mendoza said, making it challenging to piece together a timeline. Investigators plan to reach out to family members and maintenance and security workers from the gated community to figure out the last time anyone saw or spoke to Hackman or Arakawa.

Authorities do not believe the home had any surveillance cameras, Mendoza said.

Hackman appeared in a broad range of movie roles dating back to 1961, when he debuted in “Mad Dog Coll." Through the next four decades, his roles including arch nemesis Lex Luthor in the “Superman” movies and the iconic coach in “Hoosiers" helped put Hackman in the spotlight.

He was a five-time Oscar nominee who won best actor in a leading role for “The French Connection” in 1972 and best actor in a supporting role for “Unforgiven” two decades later. He also won praise for his role as a coach finding redemption in the sentimental favorite “Hoosiers.”

Sympathy and admiration for Hackman poured in from Hollywood legends including director Francis Ford Coppola, actor-director Clint Eastwood and actor Bill Murray.

Murray worked with Hackman on director Wes Anderson’s 2001 film “The Royal Tenenbaums.” Hackman gave young directors such as Anderson a hard time but brought skill to the set, Murray said.

“I watched him once do, like, 25 takes where he did it perfectly with an actor who kept blowing it every single time,” Murray told The Associated Press . “He was a great one. He was a great actor.”