The remains of an elderly couple who vanished from a California nudist ranch late last month were found in the home of their neighbor, who had been arrested on suspicion of their murders after being found in an underground bunker days earlier.

Stephanie Menard, 73, and Daniel Menard, 79, were reported missing on Aug. 25, Redlands Police said. Both were last seen at their residence in the 26000 block of Keissel Road at Olive Dell Ranch, a nudist resort RV park in Redlands, at 10 a.m. on Aug. 24. Their dog, a small white Shih Tzu named Cuddles, was also missing.

Their next door neighbor, 62-year-old Michael Royce Sparks, was arrested in connection with their disappearance the evening of Aug. 29 after he was found in a bunker beneath his home.

A search by law enforcement of where Sparks was found led to the discovery of initial remains on Aug. 30, and more were recovered over the course of the search, which ended Monday, Redlands Police said.

The remains were positively identified by the coroner’s office as belonging to the Menards on Thursday, Redlands police confirmed to NBC News.

It’s not clear what the cause or manner of death was. NBC News has reached out to the San Bernardino County Sheriff-Coroner for more details.

There has been no sign of the couple’s dog, Cuddles.

Sparks was charged Tuesday with two counts of felony murder, with a special circumstance allegation of multiple murder, by the the San Bernardino County District Attorney’s office.

After the couple disappeared, police conducted an investigation at Olive Dell Ranch on Thursday Aug. 29.

While out there, police dispatchers received a tip from a family member “indicating that the suspect, Michael Sparks, was involved in the disappearance and had admitted to killing two people and was threatening suicide,” Rachel Tolber, Redlands Police chief, said in a news conference Tuesday.

Redlands police then went to his property, and for hours tried to contact him, believing he was potentially armed and barricaded.

After he failed to show, police obtained a warrant and used a drone to enter and search the property, but still did not find him. Then they used a TAC-CAT, an armored Caterpillar tractor used by law enforcement, to break into the home. Sparks was ultimately located in a basement-type structure under the home.

He was found armed with a rifle, “which he attempted to fire in an effort to harm himself and the weapon misfired,” Tolber said. He was then taken into custody.

The search of his property, destroyed from the breaches, led to the discovery of the remains along with other evidence. The search was completed Monday.

District Attorney Jason Anderson said his office couldn’t speak on motive or what kind of relationship Sparks had with the couple.

Sparks is being held at the West Valley Detention Center. If convicted, he’s eligible for a sentence of life without parole with the special circumstance allegation filed against him.

No attorney information was listed for Sparks in online court records.