Although the lyrics describe Mengele's abuses rather than endorsing them, "Angel of Death" led to accusations of Nazi sympathizing and racism against the band, which they vigorously denied but which followed them throughout their early career. Despite the controversy and the resulting delay in the release of Reign in Blood, the song remains a live favorite, and has appeared on all of Slayer's live albums.

The song has been described as highly influential in the development of thrash or speed metal, and is highly regarded by some critics; AllMusic's Steve Huey called it a classic and the album "the pinnacle of speed metal". The half-time riff was sampled by Public Enemy in their 1988 song "She Watch Channel Zero?!"

Slayer guitarist Jeff Hanneman wrote "Angel of Death" after reading books about Nazi physician Josef Mengele while on tour with the band. He said that he remembered "stopping someplace where I bought two books on Mengele. I thought, 'This has gotta be some sick shit.' So when it came time to do the record, that stuff was still in my head—that's where the lyrics to 'Angel of Death' came from."

The lyrics are written both from Mengele's point of view and from that of a detached observer condemning his actions. They detail Mengele's surgical experiments on patients at the Auschwitz concentration camp during World War II. Mengele's explorations were conducted on such groups as dwarfs and twins, and included both physical and psychological examinations. Among the tests he performed that are mentioned in "Angel of Death" are experimental surgeries performed without anesthesia, transfusion of blood between twins, isolation endurance, gassing, injections with lethal germs, sex change operations, the removal of organs and limbs, and abacination.

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Wikipedia