Natalie Brothwell, 44, was taken into custody Tuesday at her home in Tucson on two counts of murder and child endangerment, according to the Los Angeles County Sheriff's Department. She is now awaiting extradition to California.
The children's father, Maurice Jewel Taylor Sr., was arrested last December and subsequently charged with two counts or murder involving his children, Maurice Jr. and Maliaka.
Los Angeles County prosecutors say the two older children were decapitated and the two younger boys, ages 8 and 9, were shown their slain siblings and forced to stay in their bedrooms for several days without food.
Taylor is also facing two felony counts of child abuse under circumstances or conditions likely to cause great bodily injury or death involving the younger boys.
He is set to be arraigned Nov. 10 in a Lancaster courtroom.
The victims were stabbed Nov. 29, 2020, and their bodies were still inside the family's home in the 45000 block of Century Circle when authorities arrived five days later on Dec. 4, according to Los Angeles County sheriff's Deputy Eric Ortiz.
The murder charges against Taylor do not include special circumstance allegations that could have made him eligible for the death penalty or life in prison without the possibility of parole.
Taylor faces a potential state prison sentence of 57 years and four months to life if convicted as charged, according to the District Attorney's Office.
It was not immediately clear whether Brothwell could face the same potential life prison sentence if she is convicted as charged.
City News Service contributed to this report.