A police reinvestigation into the deaths of recruits at the Deepcut army barracks has been criticised by another force, a report is expected to reveal.
Clockwise from top left: Sean Benton, James Collinson, Geoff Gray and Cheryl James
Privates Sean Benton, James Collinson, Cheryl James and Geoff Gray died at the Surrey barracks between 1995 and 2002.
A review of the Surrey Police inquiry by Devon and Cornwall Police is thought to say that detectives decided too quickly the deaths were all suicides.
There was also a "lack of focus" and guidelines "were not followed".
Pte Benton, 20, from Hastings, East Sussex, Pte Collinson, 17, from Perth, Pte James, 18, from Llangollen, north Wales, and Pte Gray, 17, from Seaham, County Durham, were all found dead at the camp from gunshot wounds.
Surrey Police was prompted to launch a second investigation after the more recent of the deaths in 2001 and 2002 prompted new questions about what was happening inside Deepcut.
In 2003 it announced that no-one was to be prosecuted over the matter, although no details of the findings of the circumstances of the deaths have yet been released to the public.
Devon and Cornwall Police were called in later that year to review the Surrey force's handling of the investigation after the families of the four young recruits questioned the suggested explanation that their deaths were due to apparent suicides.
The four young recruits were all found dead from gunshot wounds
The family of Pte Collinson have seen a copy of the report.
His father, Jim Collinson, told BBC Scotland: "They found that Surrey Police's mindset into the investigation was wrong.
"They treated the murder investigation differently as opposed to if it was a civilian death.
"They also found out that the managerial structure was very at fault, they didn't even know who actually was in charge of running the investigation."
A summary of the Devon and Cornwall report, commissioned by the Independent Police Complaints Commission and which was completed two months ago, is to be released later.
It is believed that Surrey Police will acknowledge that "mistakes" were made but play down their possible impact on the outcome of the investigation.
Responding to the leaked findings, Pte Gray's father, also named Geoff, said the whole £1m investigation by Surrey Police "had been shown to be a farce".
Mr Gray told the BBC Radio 4 Today programme that the families were shown just three pages of the 150-page report on Thursday.
"Obviously we need to see the full report. It's no good being given an executive summary," he added.
"Surrey Police told us yesterday that even though the start of the investigation was not focused, even though there were problems with the mindset, even though it did not follow government guidelines or follow the murder investigation manual, their investigation was not flawed.
"I do not believe that.
"I believe it is a rather cosy situation where you have got one police force investigating another police force."
A spokesman for Surrey Police said it was still in the process of briefing the families and it was not prepared to comment until the findings had been published on Friday.