Lori Vallow, the Idaho mom accused in the deaths of her two children, is now facing a new charge that she conspired to kill one of her former husbands.

According to New York Post, Lori Vallow allegedly conspired with her late brother, Alexander Cox, to murder her fourth husband, Charles Vallow, in 2019.

The new indictment filed against the Idaho mom was confirmed by prosecutors from Arizona on Tuesday, June 29. 

The Maricopa County Attorney's office noted that Lori Vallow agreed with his brother that "at least one of them or another" would kill her late husband. 

Because of this, the 47-year-old Idaho mom is charged with one count of conspiracy to commit first-degree murder. The two-page indictment did not provide other details. NBC News reported that Charles Vallow's filed for divorce before he died. 

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Lori Vallow Conspired With Brother in Killing Her Fourth Husband

In July 2019, Lori Vallow's brother, Alexander Cox, gunned down Charles Vallow. Cox even called 911 and reported that he killed his brother-in-law. 

However, he claimed that it was self-defense and was never charged for the death of Charles Vallow. Cox was reported to be dead due to a blood clot in December of the same year.

"Complex, difficult cases of this nature take time to properly investigate and solve," Maricopa County Attorney Allister Adel said in a statement.

Adel also expressed gratitude to the officers of the Chandler Police Department for the efforts and time they invested in the case, adding that her office is "equally committed" to bring justice for Charles Vallow's death.

Lori Vallow's Other Cases

Lori Vallow was also charged for the murder of her children, Joshua Vallow, and Tylee Ryan. The Idaho mom's fifth husband, Chad Daybell, was also charged for the murder of the two children, who were last seen in September 2019.

The Vallow's children were never reported missing by their mother. They were found dead last year. A court document revealed that a friend of Vallow alleged that the Idaho mom believed that her children turned into zombies.

Soon after, a body tightly wrapped in black plastic and covered in duct tape was discovered on Daybell's property in Idaho. Authorities noted that the skull found by the investigators matched with one of Vallow's children.

Both Vallow and Daybell face two counts of first-degree murder, conspiracy to commit first-degree murder, and grand theft by deception in the deaths of Vallow's children.

Daybell was also charged with the first-degree murder of his former wife Tammy and two counts of insurance fraud related to the collection of benefits he received after her death.

Earlier this month, Lori Vallow has been ordered by a judge to be admitted to a mental facility after being deemed unfit for trial. 

She was ordered to have a competency evaluation in March for separate concealment of evidence charges. Reports said she was ruled unfit for trial last month.

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WATCH: Lori Vallow Daybell Indicted in Maricopa County - From ABC15 Arizona