(CNN) An Idaho woman who is accused of killing her two children has been charged in the death of her former husband.
Lori Vallow was charged by an Arizona grand jury with one felony count of conspiracy to commit first-degree murder, the Maricopa County Attorney's Office said in a news release Tuesday.
The charge is related to the death of Vallow's former husband, Charles Vallow, on July 11, 2019. On that day, Vallow's brother, Alexander Cox, called 911 to report he had shot and killed his brother-in-law, according the statement from the attorney's office. Charles Vallow died at the scene, prosecutors said.
According to the grand jury indictment, Vallow agreed with her brother that "at least one of them or another would engage in conduct constituting the offense of First Degree Murder."
Cox, Vallow's brother, died in December 2019, prosecutors said. The Maricopa County medical examiner said Cox died of natural causes, CNN affiliate KPHO/KTVK reported
CNN has reached out to Vallow's attorney for comment.
Vallow is also facing charges in Idaho related to the deaths of two of her children, Tylee Ryan, 16, and Joshua "JJ" Vallow, 7.
The children went missing in September 2019. Vallow and Chad Daybell married that November. In June 2020, law enforcement officials found the children's remains on Chad Daybell's property in Fremont County, Idaho.
Vallow and Daybell were indicted on murder charges in May in connection with the deaths of the children.
Daybell pleaded not guilty to the charges earlier this month.
After a court ordered psychological evaluation, Lori Vallow was declared "not competent to proceed" with trial by an Idaho judge last month.
This decision affected Vallow's trial in Fremont County, where she is charged with two counts of conspiring to destroy, alter or conceal evidence of her two children's buried bodies.
It isn't clear if the psychological evaluation will affect her trial on the murder charges involving her children.
Correction: A previous version of this story gave the wrong age for Tylee Ryan. She was 16 at the time of her death.