In July 2014, police in Manchester arrested a 34-year-old man on suspicion of filming himself raping a child. In the video, the face of the perpetrator was hidden but his hands were visible.
Detectives felt they had the right suspect in custody, but did not have enough evidence to secure a conviction. With time running out, they turned to Dame Professor Sue Black, a forensic anthropologist who is an expert in the identification of anatomical features, including hands.
If you have been affected by any of the issues raised by this film, the following organisations may be able to help.
Produced by Craig Langran and James Stewart.
Filmed and edited by Andy Brownstone.