No, Ichor, the tax collector on spells, altered the searching spells to lead investigators to the Meagher house. Basically, this is going to appear to be an attempted assassination by them in order to kill the King and move up in the world (especially if the heir is dead.) They are so powerful that they don't really have much of a threat by their lesser constituents. However, the King is certainly powerful enough to wipe the floor with them.

I am aware that Adair is not involved, but you mentioned the downfall of the great house in your character's notes. I figured that this could be the weapon used in the tragedy.

I was thinking the Marquis could be like, "Dude, this is totally a frame-job, seriously we don't know anything about this kid you asked about. If what you say is true we should have known about him and the guard that thought it would be a good idea to use him as bait."

The guards can think, "Well, they have motive, but no means or opportunity."
However, once they leave and explain everything to the king, the king can have his doubts, "Wait just a minute, these people warp minds. Maybe they just did that to the dude that rounded up the assassin or, heck, even the assassin himself!" (which is super dangerous), and suddenly they become a threat that must be dealt with swiftly and without the normal caution they would take with other noble houses. Innocent or not, a tyrant is forced to take action, and lickity-split he is rounding up Meaghers by the cart-load to send them to their deaths. What do you think [@Dusksong]?