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The mother of two children who have been missing for months was arrested Thursday in Hawaii on a $5 million warrant from Idaho.

Lori Vallow has been charged with two counts of desertion and nonsupport of dependent children, Kaua'i police said in a statement Thursday. Police said Vallow failed to comply with a court order to produce her children to authorities by Jan. 30.

There is no indication that Vallow's children were on the island of Kaua'i, police said in the statement. Vallow's husband, Chad Daybell, was not in custody, law enforcement sources told NBC News.

–Kaua'i police arrest Lori Vallow on $5 million warrant from Idaho– pic.twitter.com/n2ghadtfal — Kaua'i Police Department (@kauaipd) February 21, 2020

The search for Tylee Ryan, 17, and Joshua Vallow, 7, began in November when Idaho police tried to conduct a welfare check on Joshua, who is adopted and has special needs, according to the Rexburg, Idaho, Police Department.

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Joshua and Tylee were last seen in September, and Rexburg police said Vallow and Daybell were not cooperating and had left the state.

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According to Rexburg police, Vallow and Daybell said Joshua was staying with a family friend in Arizona, but investigators later learned that was a lie. A witness also told police that Vallow had falsely said Tylee was dead.

Annie Cushing, Tylee's aunt, told NBC affiliate KSL of Salt Lake City that she is concerned for the safety of the children, because she believes Vallow is "unhinged."

Tylee's father, Joseph Ryan, who is Cushing's brother, was Vallow's third husband. He died, apparently of a heart attack, in 2018.

Rexburg police said they have learned that Vallow either knows where Joshua and Tylee are or knows what happened to them.

Police have also said they believe the children's disappearance could be tied to an investigation into the death of Daybell's first wife, Tammy Daybell, 49. She was found dead in her home in October, and Chad Daybell married Vallow weeks later.

Vallow's fourth husband, Charles Vallow, also died last year. He was shot to death in July by Alex Cox, Vallow's brother, during a confrontation.

Vallow and Cox were questioned by police but not charged. Cox died in December, The Associated Press reported.

Before Charles Vallow died, he filed for divorce, claiming in divorce documents that his wife believed she was reincarnated and was a god sent to lead people during the second coming of Jesus in July 2020 and that she told him that if he got in his way, she would kill him.

A lawyer who represented Charles Vallow during the divorce proceedings said in a statement that he had a "genuine fear for his life."

Other court documents, filed in Texas during Vallow and Ryan's custody battle over Tylee in 2007, revealed that Vallow was ordered to undergo a psychological evaluation after she told social workers that "death would be an option before giving Tylee to her father, Mr. Joseph Ryan, even for a visit."

Police in Kaua'i said they first received a request from Rexburg police to help find Vallow in December.

Vallow is being held in Hawaii on $5 million bail and does not yet have a court date. She will have the opportunity to waive or fight her extradition to Idaho. A lawyer for Vallow did not immediately respond to a request for comment.