The stepfather of two Idaho children who have been missing for months was arrested on a felony charge of concealing evidence on Tuesday after investigators found unidentified human remains on his property, the authorities said.
The man, Chad Daybell, was booked into the Fremont County Jail and is scheduled to appear in court on Wednesday, Gary Hagan, the assistant police chief of Rexburg, Idaho, said during a news conference on Tuesday.
The assistant chief said that an autopsy would be conducted on the remains, which were discovered by the police, deputy sheriffs and F.B.I. agents while executing a search warrant at Mr. Daybell’s home. He declined to comment further on the investigation.
A lawyer for Mr. Daybell declined to comment Tuesday night.
The children, Tylee Ryan, 17, and Joshua Vallow, whose eighth birthday was on May 23, vanished sometime last year. Their mother, Lori Vallow, was arrested in February in Hawaii on a raft of charges that included two felony counts of desertion and nonsupport of dependent children.
The missing persons case has drawn international attention because of the apocalyptic religious beliefs of Mr. Daybell, 51, and Ms. Vallow, 46, who married shortly after both of their spouses had died.
Ms. Vallow’s previous husband, Charles Vallow, was shot and killed in Arizona last July by Ms. Vallow’s brother, Alexander Cox, who told the police that his brother-in-law had hit him in the head with a baseball bat and that the shooting was in self-defense. Ms. Vallow and her first husband were estranged at the time.
Mr. Daybell’s wife Tammy Daybell, 49, was found dead last October in her home in Idaho. The authorities initially said that she appeared to have died of natural causes, but her body was exhumed on Dec. 11 after the authorities in Idaho began to question the circumstances of her death and whether it might have been connected to the disappearances of Tylee and Joshua.
Mr. Daybell and Ms. Vallow turned up in Hawaii in January without the children. The Kauai Police Department said it had served Ms. Vallow with a court order to take her children to the Idaho Department of Health and Welfare. But Ms. Vallow and the children never appeared at the Idaho agency.
The grandparents of Joshua, who is known as JJ, have offered a $20,000 reward for information helping them locate the children.
“Our feelings of extreme anguish and despondency were prevalent throughout the period approaching JJ’s 8th birthday,” Kay Vallow Woodcock, Joshua’s grandmother, wrote in a Facebook post on May 30.
In divorce records obtained by the Phoenix television station Fox 10, Mr. Vallow said that Ms. Vallow had told him that she believed she was “receiving spiritual revelations and visions to help her gather and prepare those chosen to live in the New Jerusalem after the Great War as prophesied in the Book of Revelations.”
Several fiction books written by Mr. Daybell have recurring doomsday themes. Both he and Ms. Vallow have been linked to an entity called Preparing People; its website said it aims to help prepare people for the Second Coming of Jesus Christ.