The brother of Lori Vallow , the Idaho woman under investigation for the disappearance of her two children and the suspected murder of her husbands former wife, died of natural causes, a medical examiner said Friday.

Alex Cox died in December from a pulmonary embolism, which is a sudden blockage of an artery in a lung due to a blood clot, the Maricopa County Medical Examiners Office in Arizona determined.

The 51-year-olds sudden death raised suspicions following the disappearance of his sisters children, 17-year-old Tylee Ryan and 7-year-old Joshua JJ Vallow, who havent been seen since September.