Police were continuing to question two women and two men on suspicion of murder after a man's body was found in the River Thames in Oxford yesterday.
The body was found by police teams who were searching for a missing man near the river at Sandford Lock.
The dead man has not been yet been formally identified and a postmortem examination is expected to take place today.
The Thames Valley Police helicopter, underwater search teams and specialist search and rescue teams were called to search the river and the area surrounding it.
They were alerted by a member of the public who spotted the body in the river at 11.30am yesterday.
Victoria Bartlett, police spokesman, said last night: "Police are continuing to search the area.
"I don't know how many police have been involved because this has been a missing person's investigation. Inquiries have been going on for some time.
"The police helicopter has been involved in looking for the missing man and police divers have been searching the river."
Police have been searching for Shaun Miles, 39, of Oxford, who was last seen near the river bank at Iffley Lock just over a week ago.
Mr Miles - pictured - is described as white, 5ft 10in tall and slim with dark hair.
Two women, aged 33 and 34, and two men, aged 23 and 34, were arrested on suspicion of murder in connection with the body in the river.
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