[@dragonmancer]I can see this idea making for interesting plot potential but...while with The Syndicate, he may have to resort to another form of magic than Necrommancy because The Syndicate would not like it. This doesn't mean I am telling you to get rid of his powers. I can see this character using the power under The Syndicate's nose, say, if the investigation hits a deadend and the only lead was the dead guy on the floor. I imagine him using his power to resurrect the body briefly, like few minutes, just to interrogate the one who died.

This ability can work with Medium characters too. If the corpse refuses to talk, they may be able to tap into the now active memory and get the info any way. This also works for spirits who refuse to talk.

I do not want the Necromancer class to clash with the Medium. I know they are very different but they have some abilities that overlap.

If you go this route, then your character will be the only necromaner in the game due to the overlap nightmare. The necromaner also will not  be so elaborate as you described since your character would be using other spells that replace his necromancy. But yes, I may throw in-game situations his way that may require him to come out of the box with his true powers that may surprise characters that didn't know about them.