I'm designing a character for a campaign whose role is to be a recurring antagonist. When the players first meet him, I want him to seem undeniably human. The idea is that the party will "kill" him and his body will be destroyed, only for him to be revived later and come back for revenge as Lich.
The party will be able to check him for magical effects when they first meet and I want it to be a surprise that he is a Lich. If they party detects Transmutation or Illusion magic on him or detect him as Undead it will give too much of a hint to his true nature.
Is there a way the Lich could retain a human form without magic?