The only problem with that is that Iesha was murdered 3 months prior to the start of the campaign, and Aldern didn't start the killings until he already became a ghast.
I do like the sanatorium as a way to throw them off though.
My group just finished up in Thistle top and are about to begin The Skinsaw Murders. I am a bit worried that they will suspect Aldern right from the time they get the first note. He wasn't played up a ridiculous amount, but the players haven't had any other particularly flirtatious run ins (besides Shayliss, but that was a different PC)