A great film, but some questions

Rating: 7/10 (23 February 2009)

I am NOT an Angelina Jolie fan, but found this movie engrossing nonetheless. However, crime solver that I am, there were a couple of loose ends in the film that left me wondering. First, when Ms. Collins goes to the train station to get her 'son' and realizes it isn't him, and then is bullied into taking him home, why doesn't she think to have the kid's fingerprints taken and compared to her son's? Also, at the end, when the boy is being interviewed about the escape and said he didn't know what happened to Walter, why did the police not talk to the nephew of the killer, the boy who told the story initially? He was with his uncle (or was it cousin) when they chased the escaped boys, and surely he would know if Walter was caught and then killed. It seems that the answer would have been easy to obtain, rather than have her wait years and years with no closure.