Of course these are NOT a perfect couple. They appear to be SCUM...But even SCUM don't deserve to have their child abducted/murdered. If they did there would be millions of child murders every year.
I feel much more sorry for the child than I do the parents. She was first let down by a couple of drunk, potheads, most likely passed out and couldn't hear her being abducted to her own murder.
Focus, I repeat FOCUS, on the murder of the child, not the sins of the parents...
I think it's a pretty fair bet that the child would not have been murdered had she had conscious, clear-headed parents in the home who concentrated on something other than their own carnal pleasure.
They should be charged with child neglect or whatever could be thrown at them. The remaining children should be permanently removed from their household which was obviously more pleasure palace than a home.
However, the bastard that took advange of the situation set up by these losers to murder that poor child should be given the needle.