Dan and Stephanie Menard were reported missing on Sunday.
CNN  — 

Human remains in bags have been found underneath the California home of a man accused of killing his neighbors at a nudist resort, according to police.

The remains have yet to be identified, Redlands Police Department public information officer Carl Baker said Friday evening.

Police announced earlier in the day they had arrested Michael Royce Sparks, 62, and have recommended charges against him in the deaths of the couple who lived next door to his house at a California nudist resort. Daniel and Stephanie Menard had not been seen since Saturday.

A representative from the coroner’s office is working to identify the remains, Baker said at a news conference.

The remains were found Friday in a concrete “bunker” under Sparks’ mobile home by members of the Redlands Fire Department, according to Baker.

The discovery came a day after police tore into the suspect’s home using a battering ram and searched for him with video equipment.

Sparks was found “under the home” about 9:30 p.m., Baker said.

Investigators search the home of Michael Royce Spark on Friday, August 30.

He was armed with a rifle and had barricaded himself into the home, forcing officers to remove the entire front wall of the house, Baker said. He attempted to shoot himself when officers discovered him but his weapon misfired.

“He surrendered voluntarily. I won’t say he’s been cooperative,” Baker said, adding there had been “lengthy negotiations” with Sparks.

Sparks is set to appear in court Tuesday, jail records show. He is ineligible for bail, according to the records. He has not spoken to law enforcement since his arrest, Baker said.

CNN has not been able to identify an attorney for Sparks or locate family members.

The Menards were last seen on Saturday and reported missing on Sunday, police said. CNN affiliate KCAL reported Daniel Menard was 79 and his wife 73. Daniel suffered from dementia and was diabetic, the police department said on Facebook.

Their unlocked car was found near their house at the Olive Dell Ranch. The ranch’s website says it is “Southern California’s favorite nudist resort for families and couples.”

Police say they got a tip alleging the neighbor was involved when they were following up on the missing person’s report.

“We obtained a search warrant to try to locate and contact the suspect. That’s his home,” Baker said Thursday. “He was not responding to our efforts to have him come out.”

There was no information about the couples’ dog, a white Shih Tzu named Cuddles, Baker said.

Redlands police locked down the suspect’s house in the Olive Dell Ranch RV Park, about 65 miles east of Los Angeles.

Irene Engkraf, who identified herself as the concerned neighbor who called police, told reporters ahead of the Friday news conference she and the couple usually attended Sunday church service together.

But last Sunday, the couple didn’t turn up for church and she saw their car sitting “abandoned.”

Using a spare key to enter the Menards’ home, Engkraf saw Stephanie Menard’s purse and both of the Menards’ phones. Then she called 911 and started calling hospitals, searching for news of her friends.

“It felt so odd not to have them sitting right next to me” at their usual Wednesday Bible study, she said. “But I know God’s with them. He’s with them wherever they are.”

She described the suspect as a “loner” who “didn’t socialize so much.”

CNN’s Paradise Afshar contributed to this report.