Twist for the sake of a twist?
I'm starting to get tired of those.
The twist was not bad on itself, but when done so sloppily and just before the end, it becomes insipid and confusing.
The movie was short... they could have cut some unnecesary torturing footage and then have the parents realize they got the wrong man (it's hard to believe they wouldn't in the first place, as the killer's face probably would haunt them forever and she even had the chance to scrutinize his eyes).
Then, making them see what to do next would have been VERY interesting... they could have gone trying to catch the real killer themselves before the police did, try to ammend for the other prisoner somehow, then disappear from public sight... I could see a lot of potential with having the same twist in the middle of the film.
But no. It became just a confusing non-satisfying rushed mess.