Photograph of Carlos from a fake passport under an assumed name, circa 1974IN THE END, IT WAS CARLOS THE JACKAL’S TESTICLES THAT DID HIM IN. Having boasted of bedding more than 400 women and killing 83 people by his own hand, he was suffering from a condition known as varicocele—“essentially a varicose vein in the scrotum,” as author Joby Warrick puts it. It was 1994, and the Venezuelan-born Marxist, anti-Semite champion of the Palestine cause a…