Talk:Jack the Ripper/@comment-81.39.4.146-20180219160440/@comment-45.56.46.26-20180627232429

Ainz lent them skeletons (for mining work) and an unspecified but probably level 30 or higher undead to use in the enforcement division.

It probably wasn't a mid-tier summon like Jack, since we don't have enough evidence that Ainz had mastered making undead summons of that level persist (particularly at that point in time). However, it isn't impossible.