everything in the first season shows us he did not, unless he suddenly became Mr Hyde in that black-out period. Having said that, I was kinda expecting a twist in the end. but I'm happy it didn't happen as it would not make sense.

0.1% he did : because abstract Descartian doubt but mainly because of his sudden surge of violence with the acid throwing cellmate.

99.9% he did not : if he had done it, how come he was not smeared with blood when he woke up ? Took a shower and changed clothes ? Unless I missed something, it actually looks like a glitch in the script, since I don't think we're supposed to doubt what is shown during the first episode.

Too many suspicious people who are not investigated at all...starting with the stepfather, the financial promoter, the funeral home guy, the thugs on the street.... In my opinion he had not done it, although the shadow of his violent personality kept hidden remains. It's a very good series and done well, it is beautifully, attention to detail, framing... very good.