There are few people alive today who can recall the ominous grin of the notorious "Angel of Death", Nazi doctor Josef Mengele. Marta Wise is one of them.
"When he smiled you knew it meant danger because when he was smiling that was when he was at his most sadistic," said Wise, an 80-year-old from pre-war Czechoslovakia who lived for two months in Mengele's experimental barracks in the Auschwitz-Birkenau death camp.
Mengele, a German officer and physician, was known for conducting cruel, unscientific experiments on inmates, especially Jewish and Gypsy children. His "research" included attempts to turn dark eyes blue and studies into how twins were conceived, likely with the aim of boosting the Aryan "master race".
Most of those who came under his care did not survive.
"We lived with a family of Hungarian dwarfs with nine children," said Wise, recalling how Mengele bounced a two-year-old boy on his knee and cooed, "Call me Uncle Mengele." Then he injected the toddler with something that made his skin turn blue, Wise said.
She and her sister, she said, were also injected with a substance, although they never discovered what.