According to a criminal complaint filed Monday in Fremont County, Idaho, Vallow provided false information about his whereabouts and failed to present the children to authorities.
He was expected to appear on the new charges later Tuesday. CNN has contacted her lawyers for comment.
Authorities have not said how the children died and no one has been accused of killing them.
According to a probable cause affidavit, JJ was found “well preserved” and was visually identified by officials and family. JJ’s body had been wrapped in two layers of plastic and buried under a layer of flat panels and rocks, according to the document.
However, Tylee’s remains “were too damaged by fire and dismemberment and no longer had any recognizable characteristics,” Rexburg Police Lt. Ron Ball wrote in the affidavit.
Tylee was identified “by matching an irregular jaw with an X-ray of Tylee when she was alive,” the court document says. Authorities said they are in the process of verifying the identification with a DNA test.
Daybell and Vallow are in the custody of Idaho officials. Both have pleaded not guilty to the charges related to the disappearances. Daybell is accused of concealing evidence.
Vallow was previously charged with two felony child desertion and non-support offenses and three misdemeanor counts. She pleaded not guilty.