Privates Sean Benton, Cheryl James, Geoff Gray, and James Collinson all died from gunshot wounds in unexplained circumstances at the Deepcut barracks in Surrey between 1995 and 2002.
Clockwise from top left: Sean Benton, James Collinson, Geoff Gray and Cheryl James
The army says the deaths were all suicides but this has been disputed by the soldiers' parents, who have consistently called for a public inquiry into the deaths.
A full investigation by Surrey Police did not find enough evidence for a prosecution in any of the cases, but it did call for a broader inquiry into the Army's handling of recruit training.
Subsequent investigations have criticised some training practices and care policies, but there has been no suggestion from official inquiries that there is any evidence of criminal involvement.
A review by Nicholas Blake QC highlighted failings at Deepcut - the closure of which is expected to be announced by the Ministry of Defence - but ruled out a public inquiry.
It did not reach a conclusion on the death of James Collinson because an inquest had not taken place but said the deaths of the three other recruits were probably self-inflicted.
Sean Benton, 20, from Hastings in East Sussex, was found dead with five gunshot wounds in June 1995, while on guard at a perimeter fence.
The army said he had committed suicide, and an inquest also recorded a verdict of suicide.
Private Sean Benton was found with five bullet wounds to the chest
In 2002 a former friend of Mr Benton claimed vicious verbal attacks and humiliating abuse had caused the young man to take his own life.
Trevor Hunter said: "He was an easy target because he had a croaky voice, he spoke his mind and his kit was a mess."
He said Mr Benton suffered a campaign of victimisation because "his face didn't fit".
A BBC Panorama programme claimed that one night Mr Benton was attacked by a gang wearing gas masks as he slept.
On another occasion, it was said, he was thrown through a window after falling out of favour with a sergeant for answering back.
Sean's family has rarely spoken about his death in public, but his mother Linda has in the past called for a new inquest and a public inquiry, saying she did not believe he had committed suicide.
In 2003 independent ballistics expert Frank Swann, who investigated the deaths initially for the police and later the families, said it was impossible for Mr Benton to have killed himself.
He suggested he had been shot four times from a distance and only once from close range.
Private Cheryl James, 18, of Llangollen, north Wales, was found dead with a bullet through her forehead in woodland outside the barracks in November 1995.
It is thought Cheryl James suffered sexual harassment
The Army said she had taken her own life but an inquest recorded an open verdict.
Her parents Doreen and Des believe their daughter suffered sexual harassment and violence at Deepcut.
One of Cheryl's friends said the young recruit had been forced to have sex with a corporal there.
Ballistics expert Frank Swann said it was "highly unlikely" Miss James shot herself.
He believes she was probably trying to push the gun barrel away from her face when she was shot, accidentally or deliberately.
Her family has demanded a public inquiry into the "sinister culture of bullying and intimidation" at Deepcut, and called for a second inquest.
The family also said it suspected a cover-up, after the bullet, removed during a post-mortem and which would have been a vital piece of evidence, went missing.
Mr and Mrs James are still awaiting the outcome of a probe into their complaint to the Independent Police Complaints Commission about how the police handled part of the investigation into their daughter's death.
Private Geoff Gray, 17, from Seaham, County Durham, was found dead with two gunshot wounds to his head while on guard duty in September 2001.
The army believed he took his own life, but a coroner recorded an open verdict.
Various aspects surrounding Geoff Gray's death are mysterious
Various aspects of his death have proved mysterious, including reports that a figure was seen running away from the area, and suggestions that his body was moved shortly after his death.
Ballistics expert Frank Swann said it was "highly unlikely" Mr Gray killed himself.
Mr Gray's parents, Geoff and Diane, believe he loved life in the Army and do not think he committed suicide.
"He had no girl problems, no money worries and in fact he could not have been at a better time in his life," they have said.
The Grays have consistently pushed for a public inquiry into the Deepcut deaths, and also for a new inquest for their son.
In March 2002 James Collinson, 17, from Perth, was found with a single gunshot wound through his chin while on guard duty.
The Army suggested he had killed himself but an inquest, held long after those for the other three, returned an open verdict.
His parents insist he was a happy, cheerful young man, full of pride at being a soldier and making plans for his future, and had no reason to take his life.
James Collinson was a happy young man, his parents say
They say the police told them that while no evidence of third party involvement was found, nor was any evidence of suicidal tendencies.
Ballistics expert Frank Swann said it was "unlikely" bullet wounds to the underside of Mr Collinson's chin and head were self-inflicted, but it was possible they were the result of an accident.
The Collinsons insist their son was murdered and there has been a cover-up. They have also claimed that their house was bugged after their son's death.