User blog comment:IamJakuhoRaikoben/Chapter 345: Someone's Voice, Review./@comment-4489126-20130726195736/@comment-7418318-20130726200454

Since he was talking about memories I think he needs an intact mind to cast his magic on someone, which corpses usually don't have.

Though it might be different for dead people like Mavis or Roubaul who lingered on in this world after death.