Queen Elizabeth II granted a rare "mercy pardon" Monday to Alan Turing, the computing and mathematics pioneer whose chemical castration for being gay drove him to suicide almost 60 years ago. Turing was one of the leading scientific geniuses of the 20th century, honored for cracking the supposedly uncrackable Enigma code used by Nazi Germany in World War II and considered the father of modern computer science. But Turing was also gay at a time when that was a crime in Britain and was convicted of "gross indecency" in 1952 for having had sex with a man. His security clearance was revoked, he was barred from working for the government and he was chemically castrated with massive injections of female hormones. Less than two years later, in 1954, he killed himself with cyanide at age 41. In 2009, the British government issued a posthumous apology, but scientists and gay-rights advocates wanted the government to clear him completely of the gross indecency conviction.