The death is being treated as suspicious
Police are trying to trace a caller who alerted them to the body of a man in a canal in Manchester city centre.
Officers were called to an area near Ducie Street at about 0210 BST on Friday, after reports that a man had been seen in the water.
Underwater search teams found the body and police said the death was being treated as suspicious.
Officers are keen to speak to a man who made the phone call to the emergency services when he saw the body.
'Discretion and respect'
The dead man has not yet been identified but a post-mortem examination revealed the cause of death was drowning.
Det Supt Mark Powell said: "We are still in the early stages of our inquiry and our efforts are being centred on identifying this man and his movements on the night of Thursday 2 October leading up to his death in the early hours of the next day.
"We know that this particular area of the canal is sometimes used by men looking for sex with other men and therefore some witnesses may be reluctant to come forward.
"We are not interested in why you were there, only what you saw. You can come to us in confidence and we will treat you with discretion and respect."