Here are nine of Yorkshire’s most notorious unsolved crimes.
Brian Hardwick was shot in the back of the head at Huddersfield Car Electrical Services on Colne Road where he worked. The 50-year-old's body was found on November 21, 2001, but his killer has never been found.
Anne Dunwell was returning to her home in Rotherham on May 6 1964, when she disappeared. Her body was found the next day at the foot of a manure heap near Maltby. She had been sexually assaulted and strangled.
John Gill left his home in Bradford on 27 December 1888 to collect milk. Two days later on 29 December, his mutilated body was discovered in a stable near his home. 131 years later, his murder remains unsolved.
Sign up to our daily newsletter
The i newsletter cut through the noise
A womans body was found in the bushes near Sutton Bank on 28 August, 1981. Known as Nude in the nettles, her body was exhumed on January 24 2012 in order to obtain DNA samples, but her death still remains unsolved.
Lindsay Jo Rimer, 13, disappeared on 7 November 1994 when she went to a shop in Hebden Bridge, West Yorkshire. Her body was found a mile from the town centre in Rochdale Canal in April 1995.
The death of Bradford schoolgirl Nobantu Zani in September 1995 remains unsolved. The South African-born 15-year-old was found dead at a crag known as Druid's Altar, on moorland above Bingley.
Patricia Grainger, aged 25, was stabbed, sexually assaulted and strangled. Her body was found under a bed base in a brook running through the Parson Cross estate by two teenage boys. Her killer has never been caught.
14-year-old Elsie Frost was found dead near a railway tunnel in Wakefield on 9 October 1965. She had been stabbed several times. No-one was convicted of her murder and her death still remains unsolved today.
Adam Chadwick was 20 years old when he was shot during a struggle with unknown intruders at his sisters home in Clifton Mount, Harehills, at around 10.40pm on June 24, 2008.His killer has never been found.