All the DNA findings prove is that there was someone else involved. I fail to see how this proves her mother and father's innocence.
I've children of my own and I can say with all certainty that if they were awakened by a stranger they would most certainly fight and scream. However, if I or their father were to wake them or any other family member, they might find it strange but would not likely make a fuss. What I find hard to believe is that a perfect stranger walked in, woke her up, and managed to convince her to walk quietly down the stairs.
Furthermore, I asked my children once that if they were going to leave a note for me (for whatever reason), where they would leave it. All of them replied the table. I bring this point up since it seems strange that anyone would put so important (albeit morbid) letter on the floor at the bottom of a set of stairs, where, in all likelihood it would go unnoticed or kicked out of the way. When you have a house with children in it (and even some adults) it is NOT uncommon for paper to build up around the house and get lost. Why? Because it ends up on the floor and most things on the floor become trashed or trash. I would think, someone demanding ransom, would have likely planned it all out before hand, thought through what they were going to do, and would have put some effort into where they placed the note, so as not to leave any chance that it would go unnoticed. Seems pretty careless to me to just put it on the floor. Also, wasn't the writing in the note strangely similar to the mother's when tested?
The other thing I find strange is: If you receive a ransom note stating your child has been kidnapped and you call the cops who search the crime scene why then would you, five hours later, search your own house? I would think, you would be out there (one person remaining at home in case the kidnapper calls) and the other all over the place looking for any sign of the their child. Who would re-search their own home? Someone who expects to find the child in the home. Why would they expect the child who they just learned was kidnapped to be in their own home? Because they knew full well she was murdered - not kidnapped!
Something else that doesn't sit right. They were to take a trip the next day (or that is at least how I read it). As most people know they returned at 10 pm the night she was killed and would in all likelihood have stayed up preparing for their trip (making it even later) and then would likely have plans to get up early the next day so as not to be late for their trip. So, the kidnapper just happened to know the exact window of time they would ALL be sleeping so they could saunter in, take their child, and murder her in her own home. I feel this is unlikely given that they probably stayed up much later than the norm (with not much time to fall into a deep sleep) as many parents do the day before a trip to get ready - especially when they were already out all day and would have had no other time to prepare for the next day's trip.
Most parents I know complain about lack of sleep. Why? After having kids you tend to sleep with one eye open. Even in my two storey house with my children sleeping on the top floor, two fans, one air filter, and a humming computer in my room, I can tell when they are up. Especially when I go to bed late and haven't had much time to fall into a deep sleep. Her parents were not likely in a deep sleep given the lateness of their return home and the trip planned for the next day.
This last thing I found to be odd about the whole case was the fact that the person who asualted and killed her, dressed her afterward. Serial killers aside, everything I have read or know about kidnappings suggest that many victims are found dumped with little regard afterward. It seems more likely to me, that the individual who killed her had a relationship with her (as twisted and sick as it was) and therefore felt compelled to dress her attributing as much honor to her as their sick and twisted mind could muster - most likely out of guilt and remorse.
I believe all the DNA evidence shows is that there was another individual involved besides her parents. I believe they were likely involved in a much bigger plot - likely child porn -and the individual's involved were in such positions as to render both mother and father silent even after such a horrendous and tragic act. She was not likely intended to die and something went horribly wrong.
Even kidnappers who take children directly from their homes remove themselves from the home with their victims - never heard of one killing the victim in their home and then leaving a ransom note. If the murderer intended to kill her they would have done just that without the note. If they intended to kidnap her for ransom, they would have gone as far away from the house as possible. How in all of this, did someone manage to not only kill this little girl in her house but torture her so that not one other person in that home heard a thing?
This little girl deserves to have the truth be known. It isn't fair to rule out all other suspicious evidence based on new evidence that only suggests another person was involved - it doesn't prove this individual acted alone!