Who is Alex Dekel from Children of the Flames: Dr. Josef Mengele and the Untold Story of the Twins of Auschwitz and what is their importance?

Unlike most of Mengele's victims, Alex Dekel was not a twin. Mengele selected Alex because of his Aryan features. Alex recalls watching as Mengele performed surgery on different sets of twins without anesthesia. After the war, he became obsessed with locating Mengele, and he often spent days and weeks following clues to Mengele's whereabouts. When he heard that Mengele was believed to be dead, Alex had a heart attack and died.