Talk:Jack the Ripper/@comment-81.39.4.146-20180219160440/@comment-45.56.46.26-20180824215147

It was at the end of Vol 3 that we learn Ainz's experiments with summoned undead based on human corpses had reached the point of determining that those over level 40 couldn't be be made persistent by use of a human corpse.

We don't know the level of Jack the Ripper, it seems likely it could be anywhere from 30-60. That means odds are it is over level 40, and thus cannot be made persistent with human corpses.

We never found out the exact results of experiments with demi-human corpses, but apparently during Vol 4 Ainz decided that they weren't enough better than human corpses to matter. He also turns Guu into a disposable zombie rather than using him for a persistent high-level undead, suggesting that corpses of any race are pretty much interchangeable for any purpose other than making zombies.

Soul Eaters seem to be a popular one because apparently they can start out as level 35ish and then become much stronger as a result of absorbing souls with their point-blank attack. Death Knights are favored for their level 40 defense. Jack the Ripper seems to have had superior attack power and speed, but if it's over level 40 then it's not much good.