Okay, here's the way I see it now:

Pancho was Lefty's father. Lefty shot him in a fit of Oedipal jealousy and took off back to Mom in Ohio, which (take it from one who's lived there!) one mother of a state. Now, as we all know a "Lefty" is also known as a "Southpaw"...or "S'Paw."

Motive, opportunity...it's all there.

Come clean, Spaw. Admit it. Get it off your chest. Once you do it will stop eating away at your innards.