Go behind the scenes of police investigations to find out how forces up and down the UK have solved some of the most puzzling cases.
How detectives caught Matthew Hamlen, who brutally murdered a Hampshire pensioner.
Jim Attfield was murdered in Colchester. Three months later another body was found
James (Jim) Attfield was murdered in 2014. Take a look how Essex Police caught his killer
Christopher Hampton was given a life sentence, 30 years after the crime.
In Bath 1984 a young woman was found raped and murdered minutes from her front door.
The hit and run which killed Thomas Sippel-Dau and how police caught the driver.
How detectives caught a violent rapist who terrorised the streets of Leeds.
Jane Harrison disappeared in 1995. It would take 18 years to prove who her killer was.
How police caught the man who murdered Simon Holdsworth in Sheffield