An independent police force is to help investigate the death of a Special Branch officer during a police raid in Manchester.
DC Oake was buried with full police honours at Manchester Cathedral
Greater Manchester Police has asked Merseyside Police to join the Health and Safety Executive's (HSE) inquiry into the death of Detective Constable Stephen Oake.
The 40-year-old, from Poynton, Cheshire, died after being stabbed during a raid on a flat in Crumpsall, Manchester, in January 2003.
A man, who cannot be named for legal reasons, has been charged with his murder.
Chief Constable Michael Todd, of Greater Manchester Police, said: "We have been extremely co-operative and open with the Health and Safety Executive. We have nothing to hide.
"In fact, to ensure that the process is seen to be as thorough and objective as possible, we have asked Merseyside Police to take on the role that we would normally perform alongside the HSE in examining the issues and procedures."
A spokesman for the HSE said: "Merseyside Police is carrying out a joint investigation with the HSE into the death of DC Oake, but it is far too early to rule in, or out, any particular course of action."
It is normal procedure for a police force to help the HSE investigate any sudden deaths at work in case of possible criminal proceedings.