RSBM
I'm looking at it a different way, I guess.
If someone murdered one of my kids -- I know I'd be in incredible pain, and probably anger for a good long while as well.
But not only did both sets of parents lose a child -- the Laundries bear the additional burden of having to face that their child was a killer.
That's adding a whole 'nother emotional burden--because they don't even get to have good memories of their child. They don't get to watch old videos and have warm feelings because their child did something that erases all those feelings. Like the Petitos, I'm sure the Laundries grieve for their son whom they will never see again, but unlike the Petitos, they don't have the privledge of putting BL's photos on the mantle and acting proud of him when visitors comment. Instead, they will bear a shame for something that wasn't their fault.
And, because of that shame, they will likely never be able to grieve their son outwardly. I think that's a horrendous burden to bear.
So, in MHO, both sets of parents are victims, but the Petitos can move forward and hold their heads up -- the Laundries don't have that prerogative.
I can't think of anything worse than losing my child. Except perhaps losing my child and finding out he/she is a murderer.
They walk in very lonely shoes.