User blog comment:PcRetro/So are Sternritter Human or not?/@comment-1387259-20131006215546/@comment-8669536-20131013093559

It has been stated that Sōken Ishida was already dead when he was taken to Soul Society by the Shinigami; therefore he was dead when Mayuri experimented on him (chapter 46). And it was stated that Mayuri experimented on Quincy Souls, not living Quincy (chapter 123).