They will be able to find a few photos and posters here and there from the old circus. There's no one named Fenix Down identified in any posters, nor is there anyone who looks particularly like him. They will find evidence of Charles Moore being part of the circus during its heyday, though. He appears to have been a magician and one of the smaller acts for the circus. The owner of the Smoke and Mirrors Circus is identified as a man named Abraham Abernathy. Assuming they go digging on that line, they'll find evidence that he was rumored to have been involved with the occult and that his circus was haunted by misfortune. Strange performer deaths and disappearances and the like. That's about as far as they'll be able to get due to details from that time being scant.