The Professor
"You're the only butler?"
"Yes, sir." Professor Layton sat on a white wicker chaise on the large porch outside the house while the butler stood attentively beside him. In the distance, the late afternoon sun hung low in the sky.
Layton stroked his chin for a moment before standing up. He turned to address the butler. "Wadsworth, would you be so kind as to phone Inspector Chelmey at Scotland Yard? Please ask him to meet us here, and to let him know I have found something of interest in one of the rooms."
As if by butler instinct, Wadsworth snapped to attention and gave a quick bow. "Right away, Master Layton. Anything else?
"Yes, Wadsworth," Layton replied over his shoulder as he stepped inside. "Let him know that there's more to our suspects than meets the eye."
What did Layton find? Where did he find it?
Hint 1:
Layton has encountered six suspects along the way. Who are they? Also this is the metapuzzle, so it will use all of the puzzle answers.
Hint 2:
Layton noticed that each suspect shared a similar trait, which helped clue him in on how to find the right room.
Hint 3:
Despite how it seems, this puzzle is based on a game that has nothing to do with Professor Layton. Once you determine that other game, think about why there are exactly nine puzzles.