Jose Breton was being held under suicide watch at the Alcolea Prison in Cordoba, ThinkSpain reported Thursday.
Breton's children, Ruth, 6, and Jose, 2, vanished last October during a weekend visit with their father. He said they had apparently been kidnapped while he was in a park in Cordoba with them.
Private investigators hired by Breton's wife, Ruth Ortiz, concluded that bones found in the ashes of a fire Breton lit on his parents' property were the remains of the children. They said the fire had been designed to burn hot and quickly consume anything placed in it.
The National Toxicology Institute issued a report agreeing with the investigators' findings, leading to formal charges of murder.
Psychiatrists who evaluated Breton called him "clever, cold, manipulative and suicidal."
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