Cthulhu flux metamorphosis/ madness clarification
He's still an investigator.

When you attach a Creeper to a Keeper that is also an Investigator, it doesn't suddenly stop being an Investigator. There are two reasons for this:


Investigator is an icon, not a special power, so Madness does not remove it. (Attaching a Creeper to something with Doom icons doesn't remove those Doom icons, either.)
Just because they're stark raving mad doesn't mean they've stopped investigating or stopped being human. (Unless the Creeper is Metamorphosis. But even then, they're still an investigative... being.)


The "special powers" are the ones printed on the card in addition to the standard Keeper text, like the power that the Federal Agents have to discard any Creeper by discarding themselves from play. So the Federal Agents can't discard themselves to remove the Madness that they've been afflicted with (regardless of how appropriate that would be).