I have been reading about this for the past hour or two. I feel so, so sad for Anna's Mom and can not even imagine losing my son. I will give an honest opinion after reading everything. That Brody man sounds very, very strange and it is sad to hear Anna's bio-father was brainwashed by him. The thing that leads me to believe they may have been involved was the suicide by Anna's bio-father after Mr.Brody died. It was almost as if, without the restraints of him the guilt overtook him. Or it could have been a mentaly ill man feeling lonely and hopeless after the loss of his only "friend". Also, the fact that the bio-father was overheard by Anna's step-father saying, "The Tot is dead". Now, it could have been a miscommunication or a muffled sentence but if it wasn't and the step father is quite confident that's what he said than wow.
What leads me to believe it is a stranger abduction is that a few other children went missing around the same time as Anna. Also, it makes sence for a predator to be lurking in the bushes around her home and waiting for his chance for her to get off of the bus. However he would have had to have had a car to take her in. The incident that Anna's brother reported about the couple trying to get Anna in the car? Too much of a coincidence to not have been related, in my opinion if this man's memory serves him correctly. What the couple would have wanted from Anna, God only knows but there could still be hope she is alive.
The motive for the bio-dad and Mr.Brody to have taken Anna is, to me, lacking. They may have been mentaly ill but that wouldn't make them murderers. Unfortunately I am inclined to believe Anna may have been abducted by a child predator. What documents could Anna's bio-father have destroyed that could have incriminated him and Mr.Brody? False passports for Anna? It seems like a long stretch but, I pray Anna is safe wherever she is.