Civilian staff are being used by police forces to investigate serious crimes, it has emerged.
The new workers have already been sent to interview rape victims and investigate murders after just six months training, according to officers' groups.
It is the latest in a process of workforce modernisation schemes set up by police forces across the UK to save money and free detectives from routine duties.
Pilot schemes started on the use of civilian investigators in 2005 and chief constables have expanded the schemes, saying they have been successful in releasing warrant-card holding detectives and saving money.
Simon Reed, vice-chairman of the Police Federation, said the CID was deep in the process of being civilianised.
"Without doubt the 'thief in the night' is the civilianisation of the service and the enhanced investigation role is included in that process," he told Police magazine.
The Home Office said the deployment of civilian staff was an operational matter for each police force, with some having expertise in specific areas such as finance.