Can't remember the title of this movie?

I remember this movie was a recent movie around a few years back. It was a mystery movie about a detective and his wife losing their child(son or daughter cant remember) and one day the detective has to go to this construction site where some workers found a box containing a skeleton. The detective thinks is his families child and they send the body to be investigated. The movie then tells the story about the true identity of the skeleton as it belonged to a mentally ill boy. The boy was traveling with his father who went to the city for work. I remember the father and his children had gone to relatives house and the relatives said they could only raise all his children except the mentally ill boy. The father then took the boy to the city where he found a job as a construction worker. There was a scene where the father told the boy not to leave the car but he did because of a reason i forgot and he almost got abducted. Later on in the movie, the dad goes to a bar where this married woman flirts with him. They talk and later have sex while the boy is in his dads car. The abductor then takes the boy. Later on the father visits back the bar and finds the married woman and his husband. The husband says something along the lines of the town is better off without the retard, and then a fight initiates. The father never finds his son, and his other children that are aged tell the story that his father never truly forgave himself and died with guilt in his heart. The story goes back to the detective as he finds out about the skeleton being the mentally ill boy. He then goes to a prison where a very old pedophile is jailed for life. They then interrogate him and ask him if he had killed the boy. The old man then admits that he did and we later find out the old man was one of the construction workers that worked with the mentally illed boy's father. I'm dying to see this classic again so please heeelp!