The force has been dealing with several murder cases

The force's resources are currently stretched because of a number of murder investigations.

In Devon, large numbers of officers have been dealing with the deaths of Janet Wickenden and teenager Alicia Eborne.

In Cornwall, teams have been investigating the murders of Joan Roddam and Carol and Graham Fisher.

'Considerable experience'

The four recently retired senior investigating officers have been recruited on a temporary basis.

Their work will be part of a regular review into ongoing and historic undetected murder investigations in accordance with national policies.

Devon and Cornwall Police said the reviews often prove effective and always assist other senior investigating officers dealing with crimes.

Ex-Detective Superintendents Mike Stephens and John Smith, plus Ex-Detective Chief Inspectors Clive Burnell and Jim Foley, are all to work with the Force Criminal Case Review Unit based at the constabulary's headquarters at Middlemoor.

Assistant Chief Constable Steve Pearce said: "The former detectives have considerable experience in managing and leading murder investigations and have all conducted reviews into undetected murders in Devon and Cornwall and other forces nationwide."