Highly-respected former homicide detective Ron Iddles is being investigated by professional standards following a complaint.
Police chief Graham Ashton confirmed the news with Neil Mitchell on Thursday.
The complaint relates to the investigation surrounding convicted police killer Jason Roberts.
Mr Iddles, who grew up on a dairy farm in Rochester, maintains his belief that Roberts did not murder Sergeant Gary Silk and Senior Constable Rodney Miller with Bandali Debs in 1998.
“There is a complaint,” Mr Ashton said on 3AW Mornings.
“I can’t say who put in the complaint, but a complaint has been lodged.”
LISTEN: Click PLAY below to hear the interview on 3AW Mornings
Mr Ashton said it related to the “manner of how the investigation” was conducted.
Mr Iddles currently holds a government role.