Surrey police officers who investigated the deaths of four young soldiers at Deepcut army barracks are being investigated themselves.
Clockwise from top left: Sean Benton, James Collinson, Geoff Gray and Cheryl James
The force has asked Devon and Cornwall Constabulary to carry out a review of its inquiry after families of soldiers who died at Deepcut raised concerns about the case.
Surrey Police carried out a £1m, 15-month investigation into the deaths of the soldiers who died of gunshot wounds at the Surrey base over a period of seven years.
The force published its report in September and said there was no evidence of foul play in the four deaths.
But that went against evidence from an independent ballistics expert, hired by the families, who said some of the soldiers could not have shot themselves.
Human rights campaign
One Surrey officer among the 34 officers working on the case resigned from the force in September, amid allegations of "inappropriate behaviour".
A spokeswoman for Surrey Police said calling in the outside force was "in line with national best practice".
"We have asked them to look into aspects including mindset, collusion, use of MoD officers and inappropriate behaviour by Surrey officers, about which some families have raised concerns."
Amnesty International has backed calls for an independent inquiry, the creation of an ombudsman looking at all non-combative deaths in Britain's armed forces and an end to recruiting people aged under 18 years old.
Public inquiry calls
A Devon and Cornwall Constabulary statement said: "The Devon and Cornwall Constabulary has been asked by the Surrey Police to carry out a limited review of the investigation into the deaths at Deepcut, in Camberley, Surrey.
"The review is at an early stage so it would not be appropriate to comment further at this time."
The soldiers who died at the barracks between 1995 and 2002 were Private Geoff Gray, 17, from Seaham, County Durham; Private Sean Benton, 20, from Hastings, East Sussex; Private James Collinson, 17, from Perth, Scotland and Private Cheryl James, 18, from Llangollen, north Wales.
The Ministry of Defence said they had committed suicide, but the families have not accepted this.
They have been campaigning for a public inquiry into the deaths.