SANTA FE, New Mexico — An investigation is underway after actor Gene Hackman, 95, and his wife, Betsy Arakawa, 64, were mysteriously found dead alongside a dog in their Santa Fe, New Mexico, home, authorities said.

The couple was found Wednesday afternoon during a welfare check after their neighbor called and was concerned about their well-being, according to the Santa Fe County Sheriff’s Office.

Their deaths were “suspicious enough in nature to require a thorough search and investigation” due to all of the “circumstances surrounding” the scene, according to the search warrant affidavit.

The Academy Award-winning actor was found on the floor in the mud room, according to the search warrant. It appeared he fell suddenly, and he and his wife “showed obvious signs of death,” the document said.

Arakawa was found lying on her side on the floor in a bathroom, with a space heater near her body, according to the search warrant. Her body showed signs of decomposition, the document said.

On the counter near Arakawa was an opened prescription bottle, with pills scattered, according to the search warrant.

A German shepherd was found dead about 10 to 15 feet from Arakawa, the document said.

But two other dogs were found alive. One healthy dog was near Arakawa and the other was located outside, according to the search warrant.

The Santa Fe City Fire Department found no signs of a possible carbon monoxide leak or poisoning, the document said. If there was carbon monoxide at the scene, it could have vented out of the home through the open front door before responders arrived.

New Mexico Gas Company also responded and “as of now, there are no signs or evidence indicating there were any problems associated to the pipes in and around the residence,” the document said.

A maintenance worker who initially responded to the home found the front door open, according to the search warrant affidavit. But there were no signs of forced entry and no signs items were taken or rummaged through, the document said.

Their manner and cause of death are not known, the document said.

The sheriff’s office said foul play is not suspected.

This is a developing story. Please check back for updates.