Meh. The "go low level" advice is sort of a cop out: "To make a D&D murder mystery, just make sure your party can't do any of that D&D stuff, so it's just like any other murder mystery."

It's more of a D&D murder mystery if you figure out how to make it interesting even though players have powers to read minds, etc.

And it's not wrecking the game for the villain to be immune to truth and mind-reading spells, or for the victim to be unavailable to raise dead (maybe because their soul is stolen). There are plenty of other minds to read and lies to detect.

The adventure should start with exposition NPC's saying, "We tried raising the victim, Zone of Truth, and Detect Thoughts, and we got no nowhere. We suspect the villain is immune to our mind magic, but we can't tell who it might be."

Zone of Truth games can be a lot of fun when everybody has something to hide or an enemy they'd love to make look guilty. "I'm sure Bob did it" isn't a lie if Alice thinks he's as wicked as that.