Gaol is statistically where people with low literacy rates end up.
It's not in that particular article, but see here for more:
"And though the right thing to do would be to try to find the man and make amends, Wahlberg says, he admits he hasn't done so -- but says he's no longer burdened by guilt."
Even worse, I've read before that he lied about apologising in a court appearance at one point in order to get a more lenient sentence.
The sentencing memorandum is here.