A man who was arrested on suspicion of murder after a fisherman's body was found in the River Thames has been bailed.
The victim, who was thought to have been fishing before he disappeared, was discovered in the water in Walton-on-Thames on Thursday.
A post-mortem examination on Friday determined that the man, who is yet to formally be identifed, was killed as a result of trauma to the head, Surrey Police said.
A 25-year-old man who was questioned in connection with the death on Friday evening has been bailed until September 29.
The Surrey Fire and Rescue Service had conducted the search of the river after concerns were raised about the missing man's safety.
The remains of the man, who was in his 40s. were found at about 4.45pm.
Senior investigating officer, Detective Superintendent Adam Hibbert, said: "This was an appalling incident where the victim sustained significant, and ultimately fatal, head injuries.
"A detailed and extensive investigation is continuing to establish the circumstances surrounding the incident and we are determined to bring those responsible to justice.
"The area is popular with fisherman and dog walkers and I would urge anyone who was in the area on Thursday and may have seen or heard anything out of the ordinary to contact Surrey Police as a matter of urgency.
"Our thoughts remain with the man's family at this extremely difficult time and on their behalf we are continuing to ask that their privacy is respected."
Anyone with information is asked to call 101, quoting Operation Briar. Alternatively, the independent charity Crimestoppers can be contacted anonymously on 0800 555 111.
