i dont think u ever find out why he was originally sent down, but during season 4 when he makes the deal with potter u find out he was sentanced to 6years in 1998 but due to all the stuff he's done for samcro whilst he's been inside as Zeigen on the Liste bobby reads in s4 e12 his time was increased to 30years, then life and now death row
His character has always been in jail on the show. I'm not sure if we actually get to know his original crime but in season 1 i'm pretty sure it's known he's a lifer. From the end of S1(smashing Stahls nose) and then onward in the Weiter seasons Otto has committed murders in prison which he has then gotten Mehr and Mehr time for and i think in season 4 it's we find out he's on actually on Death Row.
