Mengele was infamous for his medical experiments in the deathcamps, especially those he carried out on twins. He injected dye into their eyes to change their color and sewed them together in an attempt to create artifically conjoined twins. He ordered them killed simultaneously and then dissected them to examine their organs.
After the war, Mengele fled Germany and found his way to Argentina, as did many other Nazi perpetrators. Informants working with Mossad had seen him when the agents were in Buenos Aires. Mossad was able to locate the apartment he shared with his wife, and on one specific day even knew he was at home. But the next day, Mengele and his wife left the apartment for what the Mossad agents believed would be a temporary absence. By that time, the Israeli agents had already taken Eichmann into their custody and were holding him in a safe house while they waited to get him out of the country. They feared that if they waited for Mengele to return, the Eichmann operation would be discovered. They decided it wasn’t worth the risk.
Eitan said, “After Eichmann’s capture was made public, he disappeared entirely.” Mengele eluded capture for 14 years, only to drown in Brazil in early 1979. Experts identified the body six years later.
Sources: Haaeretz (September 3, 2008)