A few quick thoughts:
1. None of us were at the crime scene (or, for that matter, in the courtroom to hear the evidence) so we will never really know what happened when the young couple was killed. Pettaway was found not guilty because: a) he did not do the crime; b) the prosecutor screwed the proverbial pooch; or c) the jury panel was comprised of idiots and suckers. Anyway, the trial is over, and justice has been at least half-served, since one perp has been convicted.
2. That being said, I agree that Pettaway and his family are odd spokespersons for anti-drug campaigns, and I think a cooling off period would have been advisable. Of course, this family seems to be too wrapped up in their own dysfunctional world to give much of a s**t about anyone else, so I am not surprised.
3. As for Pettaway's mother whining about how Pettaway needs a "second chance," he already had that. And a third chance. And a fourth chance. And a fifth chance. How many times is the dude going to screw up before he gets it right? Pettaway may or may not have killed Lisa Straub and Johnny Clarke, but he already has a rap sheet longer than a roll of single-ply toilet paper. I am sure that if (when?) he next gets in trouble, there will be very little empathy from judges and juries.