Ha, you're probably right about Liz!
Sheriff Patterson guessed that that since it was Roger's great uncle, it must've been a portrait of Benjamin (which was weird), and I think Roger just looked annoyed. So he didn't confirm or deny that it was his name.
The portraits in the drawing room during 1897 are, left to right, Jeremiah, the one we nicknamed Leonardo, Isaac, Theodore and Benjamin-- who looks nothing like the guy in the foyer.