The Angel of Death
Josef Mengele earned his apt moniker, 'The Angel of Death', while working as temporary relief for the Doctor of the Auschwitz Concentration Camp. This small assignment would prove to be a permanent one, at least for about two years, until the camp was abandoned before the advancing Red Army. While he is one of the least known Camp officials, his experiments and the things he did left a lasting impression upon his patients.
Mengele's early life was rather dull, and unpronounced. He had no extreme drive, nor personal tragedy. By all accounts, he was just a regular person, working towards a Doctorate in 1935. His chosen field of study was Anthropology (not medicine). However, he studied under Dr. Von Verschuar. The Doctor had an immense interest in twins, which he would pass on to Mengele.
Mengele joined the Nazi Party in 1937, this was after the rise of the party, and even the Night of Long Knives. So, at this point, the Party was politically fashionable, yet sterilized of internal resistance. Therefore, we can safely assumed, though he joined, he had no real political motivations or ambitions.
During the War, Mengele first served in the regular German Army, before volunteering for service with the Waffen SS, as apart of their Medical Unit. During this time, he eventually became temporary Camp Doctor of the Auschwitz Concentration Camp. This is where, what could have been a very unassuming life, takes a drastic turn.
Mengele personally selected from the Camp Inhabitants, to be housed and treated separately, so that he could reserve these people for bizarre medical experiments. He would inject chemicals into the eyes of children to see if it caused eye colors to change, he would amputate limbs, perform vivisections on pregnant women, often, without the use of anesthesia. Many people, including other SS Members, also noted the lack of scientific basis for many of these 'experiments'.
Mengele also has a fondness of twins, and focused many of his experiments on these people. He even went so far as to surgically connect to twins, in the attempt to create artificial Siamese Twins. What possible scientific use this could have had is unknown.
Mengele in Argentina
There is a bit of confusion about what happened to Mengele after the war. The common accepted theory is that he was smuggled out of Germany by the ODESSA group, and went on to live in Argentina, among a group of German Nationalists who were, in reality, former SS and all Nazis dedicated to Hitler.
This theory has gained the most acceptance.
However, recently, author Annie Jacobsen has suggested that Mengele was actually living in the Soviet Union, and at some point, was involved with the creation of a grand hoax. She claims that this project was to convince America it was under attack by extraterrestrials, and led to the event at Roswell, New Mexico.
While it seems highly unlikely that he ended up in Russia, to help perpetrate a UFO fraud, the other option seems just as conspiracy ridden. We know Odessa existed, and we know Mossad thought they had him, but only didn't pursue him in Argentina, out of fear of an international incident.
Together, this gives me an idea of what really happened.