A newlywed Idaho couple under investigation for the disappearance of the wife’s two children have been tracked down to Hawaii and given until Thursday to produce the two kids, authorities said Monday.

Christian doomsday writer Chad Daybell and his wife of three months Lori Vallow were located on the island of Kauai on Saturday and served an order of petition to physically produce Tylee Ryan, 17, and Joshua Vallow, 7. Both kids have been missing since late September, authorities said.

A warrant to search the couple and their vehicle was also carried out on Sunday. The result of that search has not been disclosed, though no local charges or warrants have been issued for the couple’s arrest, Kauai’s police department said.

The couple has been repeatedly described as uncooperative in authorities’ search for Vallow’s children. Lori Vallow is the adopted mother of Joshua and the biological mother of Tylee. There is no evidence that either child was ever in Hawaii, Idaho’s Rexburg Police Department said in a statement.

These latest developments follow federal and local authorities carrying out a search of Daybell’s home in Salem, Idaho, earlier this month.

In addition to looking for clues into the whereabouts of his two stepchildren, authorities were investigating the sudden death of his previous wife, Tammy Daybell, in the home back in October. Chad Daybell married Vallow just two weeks after Tammy’s death.

Tammy was initially determined to have died from natural causes, with an online obituary for her describing her as having “passed away peacefully in her sleep.” Following the children’s disappearance, her body was exhumed on December 13 for further testing. Fremont County Sheriff Len Humphries told East Idaho News that the results of that autopsy are still pending.

Lori had previously lived in Kauai with her former husband Charles Vallow, who died in July, Arizona Family reported.

Charles Vallow was estranged from his wife when he was fatally shot in an altercation with Lori Vallow’s brother, Alexander Cox, at the Vallows’ home in Chandler, Arizona, police say.

Cox maintained that he shot Charles Vallow in self-defence after he came at him with a baseball bat while refusing to leave. Vallow’s son, stepdaughter Tylee and his wife, Lori, were at the home at the time of the shooting, according to police documents.

Cox was not arrested or charged in the shooting but later died in December from unknown causes. The results of an autopsy are expected to take several weeks or months, police in Gilbert, Arizona, have said.

Charles Vallow filed for divorce four months before his death. He accused Lori of being obsessed with near-death experiences and said she believed that she lived numerous lives on other planets before her current life. He further said that she threatened to financially ruin and kill him. He sought an order of protection and a voluntary evaluation of his wife at a mental health facility, The Associated Press reported, citing court records.

Daybell has authored several books on the end of the world and the Christian belief of Christ’s return to Earth.