Episode 12, Man in black + white photo on cabinet behind Cal's desk??

Could it be naturalist John Muir? And looks like there are large B&W photos of California nature sites on the walls of his office too.
What's the John Muir connection? Unless it's Walt Whitman who resembles Muir. I haven't been able to link Tim Roth, "Cal Lightman", John Muir, and /or Walt Whitman.