Crimewatch was an extraordinary tool for catching crooks - helping police crack open more than 5,000 cases including hundreds of high-profile murders.
The BBC crimefighting programme drew audiences of 14 million at its peak in the 1980s and such was its reach that one in three appeals ended in arrest and one in five in convictions.
The show, which reconstructed unsolved crimes in an attempt to gather information from the public, helped convict the killers of James Bulger, Sarah Payne, Rhys Jones, and the M25 rapist.
But as viewing figures dwindled in the internet age, the programme was finally axed in 2017 after 33 years of putting crooks behind bars.
Despite its success, there were some crimes that saw Crimewatch phonelines fall silent and left detectives wrongfooted - and remain unsolved to this day.
As Crimewatch celebrates its 40th anniversary - having first aired on June 7, 1984 - MailOnline looks back on the most high-profile cases the programme COULDN'T solve:
The case of Suzy Lamplugh, a 25-year-old estate agent from Fulham, south-west London, was featured on Crimewatch after she was reported missing on July 28, 1986
In a rare move, the Metropolitan Police named convicted rapist John Cannan as their sole suspect and showed a sketch bearing a striking resemblance, but there was insufficient evidence to charge him
Police forensics dig in the garden of a house once owned by the mother of John Cannon. Suzy Lamplugh's body was never found and she was declared dead presumed murdered, in 1994
Suzy Lamplugh
The case of Suzy Lamplugh, a 25-year-old estate agent from Fulham, south-west London, was featured on Crimewatch after she was reported missing on July 28, 1986.
The programme aired a detailed reconstruction of her last known movements that showed how she left her office to show a property to someone she knew as 'Mr Kipper'.
While she was officially declared dead in 1993, her body has never been found, and her killer has not been brought to justice.
In a rare move, the Metropolitan Police named convicted rapist John Cannan as their sole suspect and showed a sketch bearing a striking resemblance, but there was insufficient evidence to charge him.
Cannan is in prison for murder, attempted kidnapping, rape, abductions and other sexual offences. He became eligible for parole in September 2023, but this was refused in October 2023.
Cannan has previously hinted that he might confess to the murder of Ms Lamplugh, but only after his mother dies, 'to avoid causing her further grief'.
Louise and Robert Goble
Crimewatch featured the murder of two Sussex children, Louise and Robert Goble, who lost their lives in a horrifying arson attack on a house in Hastings, East Sussex, on February 3, 1985.
The reconstruction showed how at least one arsonist broke into the house and started a fire on the stairs, blocking off the family's sole route of escape.
Two men were spotted taking an oil drum out of a van outside the house in the early hours of the morning and an empty oil drum was found in the garden that did not belong to the Gobles.
Firefighters managed to rescue the children's mother, Lee Goble, and her husband Robert senior, but for the children, it was too late.
No motive was ever established for the crime, and the killer, or killers, remain at large.
Successful businesswoman Penny Bell was stabbed more than 50 times in the car park of a west London leisure centre in a horrific attack on 6 June 1991
Penny Bell
Successful businesswoman Penny Bell was stabbed more than 50 times in the car park of a west London leisure centre in a horrific attack on 6 June 1991.
The area would have been busy, with around 300 people using the leisure facilities or car park that morning, and police were astounded that the frenzied attack went unseen.
When she was found her handbag was open behind the front passenger seat and still contained all of her personal belongings and it did not appear that anything had been stolen.
Strangely, Ms Bell had withdrawn £8,500 from her bank in the days before her death. Where the money is, and who she met the day she was killed, are all questions that remain unanswered.
In 2019 a new witness came forward that told police that, on the day Ms Bell was killed, they saw a man in his underwear who appeared wet, as if he had just washed, walking across a footbridge that crosses the A40 Western Avenue in Greenford. The man has never come forward or been identified.
Despite a Crimewatch appeal at the time and again on the 30th anniversary in 2021, the frenzied attack on the mother-of-two remains one of Britain's most notorious unsolved murders.
The greatest mystery Crimewatch was unable to solve is the tragic death of one of its own presenters,Jill Dando (pictured)
Jill Dando was a beloved co-presenter of Crimewatch with Nick Ross (right)
On April 26, 1999, Jill Dando was shot dead on the doorstep of her home in Fulham, London
Jill Dando
The greatest mystery Crimewatch was unable to solve is the tragic death of one of its own presenters. On April 26, 1999, Jill Dando was shot dead on the doorstep of her home in Fulham, London.
The nation was plunged into shock when beloved presenter Ms Dando, 37, was shot by a bullet from a 9mm pistol, with the gun pressed against her head in what looked like an assassination.
Police explored numerous lines of inquiry, including theories Ms Dando was killed by a jealous unknown lover, was assassinated as revenge for her work on Crimewatch, or that she was targeted by a Bosnian-Serb or Yugoslav gang.
In 1997, Crimewatch ran a reconstruction stating that neighbours saw a white man, aged 30 to 40, about 5ft 10in with a mop of black hair, leaving the scene.
A huge Metropolitan Police investigation led to the arrest of Londoner Barry George, but after he had served eight years behind bars for murder an appeal court ruled the conviction unsafe and he was released.
The case remains open.
Kate Bushell
Schoolgirl Kate Bushell, 14, was murdered as she walked a neighbour's dog a short distance from her home near Exeter, Devon.
Kate set off from her home at 4.30pm on November 15, 1997. When she failed to come home, her bereft parents notified the police.
The murder of schoolgirl Kate Bushell, 14, remains unsolved despite a Crimewatch appeal in January 1998
A search located her body next to a field nearby and she was found with a horrific injury to her throat. Witnesses reported seeing a bloodstained man running away from the spot where her body was found.
The case remains unsolved despite a Crimewatch appeal in January 1998.
Claudia Lawrence
The 35-year-old, who worked as a chef at the University of York, was last seen near her home in Heworth, York, on the evening of March 18, 2009.
She had spoken to her mother on the phone that night and there was no indication that anything was amiss. This was the last time the pair would ever speak.
Detectives desperately probed her past, her relationships and her work life in an effort to discover what happened. Despite a £1million investigation and a number of arrests nobody has ever been charged.
While there were theories that a convicted killer may have been involved in her disappearance, police announced that they were scaling back the investigation eight years after she went missing. Her family has vowed to keep searching.
Claudia Lawrence, 35, who worked as a chef at the University of York, was last seen near her home in Heworth, York, on the evening of March 18, 2009
Lloyd Simpson
Twenty-six-year-old Lloyd Simpson worked at his family's waste paper business. On or around November 5, 1983, attackers burst into his flat in Hoxton, East London, and shot him 'execution style'.
It is believed that a nearby Guy Fawkes' night firework display may have masked the sound of the gunshots and prevented neighbours from hearing anything.
Theories surrounding the unexplained murder included gangland involvement, a connection with Mr Simpson's sideline of buying and selling used cars, and even an illegal dogfighting ring.
Despite Crimewatch's fourth episode airing a detailed video reconstruction of Simpson's last-known movements that featured his father, Mr Simpson's killer has never been identified.
Jessie James
The 16-year-old was murdered in a drive-by shooting in Moss Side, Manchester, shortly after 1am on September 9, 2006.
The teen and his friends were cycling across a park when a number of gunshots rang out. The group dispersed but unfortunately Jessie, in the panic, cycled towards the gunman and was hit.
Jessie, who was hit by three bullets at close range, was not part of a gang and police believe his tragic death was a case of mistaken identity.
A Crimewatch appeal was broadcast in December 2006 but the case remains unsolved, with police concerned that the lack of witnesses may be due to fear of repercussions from the gangsters involved.
However Crimewatch DID help crack a number of tricky cases wide open with the information and eyewitnesses it turned up for detectives. These include:
The murder of two-year-old James Bulger in 1993 was one of the most shocking crimes in British legal history
Jon Venables and Robert Thompson, who were only 10 at the time, were found guilty of James Bulger's murder in November 1993, becoming the 20th century's youngest convicted murderers
James Bulger
The murder of two-year-old James Bulger in 1993 was one of the most shocking crimes in British legal history.
In February 1993, James was snatched from a shopping centre in Bootle, Liverpool, while out with his mother Denise.
CCTV footage showed two schoolboys leading away the toddler by the hand. They tortured and beat him to death, leaving his body on a nearby railway line.
Witnesses identified them as Jon Venables and Robert Thompson, who were only 10 at the time, after their images were shown on Crimewatch,
The pair were found guilty in November 1993, becoming the 20th century's youngest convicted murderers. They were put in secure youth accommodation with recommended sentences of at least eight years.
They were both released in June 2001 on lifelong licence with secret identities. Venables has twice returned to prison for breaching his licence.
Sarah Payne
Eight-year-old Sarah disappeared in 2000 when was walking home from her grandparents' house through a West Sussex field. Her body was found after a 16-day search.
Crimewatch broadcast two appeals and, both times, Roy Whiting, a local man who had served time for convicting a girl, was named as a suspect.
The second appeal, in January 2001, showed a distinctive patterned curtain, fibres from which were found on Sarah's shoe. A viewer recognised it from a van which her boyfriend had sold to Whiting.
In December 2001, Whiting was convicted of murder and sentenced to life imprisonment. A campaign led to 'Sarah's Law' to enable parents to find out if somebody with access to their children has a record of sexual offences.
Rhys Jones
Liverpool schoolboy Rhys Jones, 11, was killed in 2007 while on his way home from football practice. Rhys was shot in the back by a hooded teenager on a mountain bike as he crossed a pub car park.
A month later, Crimewatch recreated his murder and Rhys's mother Melanie made a direct appeal to his killer's mother to turn him in. It led to more than 40 calls, 12 of which named the same suspect.
In December 2008, after a nine-week trial, Sean Mercer - a member of the Croxteth Crew gang - was found guilty of murder. He had been aiming at rival gang members but hit Rhys instead.
Mercer was sentenced to life imprisonment with a minimum term of 22 years. The case led to a campaign, backed by the Jones family, 'In Rhys's Name Get Guns Off Our Streets'.
Liverpool schoolboy Rhys Jones, 11, was killed in 2007 while on his way home from football practice
Sean Mercer - a member of the Croxteth Crew gang - was found guilty of Rhys's murder and was sentenced to life imprisonment with a minimum term of 22 years in 2008
Rhys was shot in the back by a hooded teenager on a mountain bike as he crossed a pub car park - his killer had been aiming at rival gang members but hit Rhys instead
M25 rapist
A string of sexual attacks on women and girls were carried out around the M25 between 2001 and 2002.
The motorway became the focus of a manhunt and an e-fit picture of the prime suspect was shown on Crimewatch.
A viewer recognised the face and directed police to their neighbour, Antoni Imiela. He was also known as the 'Trophy Rapist' because he kept his victims' clothing.
After DNA linked him to the crimes, Imiela was convicted of nine rapes, plus the indecent assault and attempted rape of a 10-year-old girl.
He was jailed for a minimum of 99 years but died of heart failure in HMP Wakefield in 2018, aged 63.
