Ok so I have this big sexy hook for my D&D story, and want to know if there is a way that I can do this while still following the rules (so that I can make sense of it)

So I will some story for it, 100 years in the past in my campaign, there was a powerful wizard named Egan. He ruled over a group of pure evil named The Black Hand, and was stopped in the past by the five glorious heroes (my parties old heroes)

I wanted Egan to make a return as a form of lich, is there a possible way? I would try and base it around some of the ancestors of the original black hand are trying to bring back to life the 100 year old corpse of their former leader in a form of ritual, is this possible at all? or is there a way around it...

thanks for reading

*Adding more information*
The average level of the group that is trying to resurrect him is level 8, with few members at most level 10.

They have enough gold to fund anything that they would require
He originally wasn't a lich, I want to see if there is a pre-made ritual to retrieve a soul from where a soul goes when an enemy dies and to place it into a body... sort of like creating a lich from an already dead creature