Officers are making a direct appeal to potential witnesses who may have vital information about the death of off-duty PC Gareth Francis.
Police investigating the death of an off-duty officer have been given more time to question two suspects.
PC Gareth Francis, 28, died on Sunday after being attacked on a night out.
Police were called to Castle Street, Edgeley, at about 1.20am to reports a man had been assaulted.
He was taken to Stepping Hill Hospital where he later died.
A post mortem has found PC Francis died from head injuries from a single punch.
Two men aged 20 and 21 were arrested and are being questioned. A third man was arrested and bailed after handing himself in to a police station.
Anyone with information should call police on 0161 856 9283.
A third man has been arrested following the death of an off-duty police officer in Edgeley, Stockport.
The officer, 28-year-old PC Gareth Francis, was walking home from a night out with friends when he was assaulted.
Two men aged 20 and 21, both from the Stockport area, had previously been arrested on suspicion of his murder and remain in police custody for questioning.
A third man, aged 20, was arrested on suspicion of murder on Sunday night. He also remains in custody for questioning.
The family of an off-duty policeman who died in an attack in Edgeley have described him as a "gorgeous son" who brought "love and laughter."
A murder inquiry is underway after an off-duty police officer died following an assault in Edgeley. Two men have been arrested.