The private firm at the centre of the Olympics security shambles is looking to hire former police officers as civilian investigators to work on sensitive, high-profile cases.
G4S Policing Solutions, part of G4S, is advertising for "civilian investigators" who will be "assisting detectives by carrying out routine yet vital tasks such as taking statements and retrieving CCTV footage".
Defence secretary Philip Hammond said today there were lessons to be learned from G4S's failure to supply enough guards to keep the Olympics secure.
"I came into the MoD (Ministry of Defence) with a prejudice that we have to look at the way the private sector does things to know how we should do things in government," he told The Independent.
"But the story of G4S and the military rescue is quite informative."
While the military delivers "contingent capability" for all scenarios, the private sector works on a very lean structure with "very little resilience", he said.
An advert on the G4S website on Tuesday read: "The roles of civilian investigators vary from force to force.
"Many forces are looking to increase the numbers of civilian investigators they employ as they can have a positive effect on police efficiency.
"Working alongside experienced serving officers building cases by gathering evidence via interviews, and telephone/internet research can be very demanding yet rewarding careers and are especially suited to retiring police officers who want to put their valued skills to good use."
A specific advert for civilian investigators in Rugby, Nuneaton or Leamington - posted last Wednesday - added that the main purpose of the role was to "investigate offences of crime, and to actively participate in a wide range of evidence gathering and crime investigation tasks".
"This is likely to be a long term contract with no specified end date and would ideally be suited to experienced ex police applicants," it said.
One of the main responsibilities will be to "undertake sensitive high profile cases enquiries with limited supervision".
Another advert for a job based in Northolt sought an investigator with a military or police background.
"You will be supporting the investigation team in pursuing criminal investigations in support of the service justice system," it said.
"You will interview witnesses, record their testimony and assist with developing investigation strategies and with the conduct of interviews after caution.
"Cases may vary covering volume, serious and major crime."
Simon Reed, vice-chairman of the Police Federation of England and Wales, said: "Domestic security must be undertaken by public servants - men and women who are fully trained and accountable for their actions.
"This is what the public want and what the public deserve.
"Privatisation of policing provides no benefit to the public, delivers a detrimental service to local communities and arguably, if the police then end up stepping in again when private firms fail to deliver, an additional cost to the taxpayer."
A G4S spokeswoman said: "Private sector support for policing is nothing new.
"For over 20 years G4S has been delivering custody facilities, temporary staff, logistic services and forensic medical services to police forces across the UK.
"For the last 10 years we have been providing retired police officers and support staff to police forces and local authorities across the UK to assist with various enquiries, particularly to help with peaks in demand.
"The staff provided always work under the direction of a police officer and at no time is G4S or any private contractor responsible for leading any investigation."
The Government has denied that bringing private firms further into policing roles could lead to the privatisation of bobbies on the beat.
Policing minister Nick Herbert has denied private firms will be involved in patrols and said in March that any suggestion that forces looking to use private firms in their work represented the privatisation of policing was "mischievous and misguided".
A Home Office spokesman said: "Policing is not being privatised - core police functions will continue to be delivered by sworn officers and no police powers will be given to private contractors beyond the limited powers allowed by the last government.
"Police officers alone will make arrests and lead investigations, and police officers will continue to patrol the streets and respond to incidents.
"However, the private sector can help to support delivery of police services better and at lower cost, for example, improving technology used by officers and providing staff for control rooms and custody centres, releasing officers for frontline duties.
"The police is and will remain a public service, accountable to the people, and any decisions on business partnering will be taken by elected police and crime commissioners, giving local people a say."
Rachel Robinson, policy officer for Liberty, said: "British policing has traditionally been a public service - not a profit-making venture.
"The transfer of sensitive policing tasks to private companies for the first time is as bad for safety as it is accountability.
"Privatisation of other core public functions tells a cautionary tale - policing powers should be left to trained professionals, not farmed out to the highest bidder."