The body of a man found in the River Thames in Oxford has been identified as Sean Miles, 37, of Herschel Crescent, Littlemore.

Detectives were waiting for the results of tests to find out the cause of Mr Miles' death last night.

As reported, the body was spotted by a member of the public near Sandford Lock at 11.30am on Wednesday.

Police were already searching for Mr Miles, who was vulnerable and had been reported missing on Tuesday.

Two men and two women were arrested on suspicion of murder on Wednesday and two men were arrested on suspicion of assisting offenders involved in murder yesterday.

Officers were carrying out forensic tests at houses across Oxford yesterday as part of their murder investigations.

Det Chief Insp Karen Trego, of Thames Valley Police major crime department, said: "The pathologist has ordered more tests to be carried out before he can give an absolute conclusion as to the cause of death.

"It was early on Tuesday afternoon that Mr Miles was reported as missing and the investigation began.

"As that developed, it became clear we were investigating something that was potentially more sinister than a missing person. That had become clear by the time the body was found."

Mr Miles had not been seen for more than a week when his disappearance was reported.

Ms Trego said: "There will be tests to see how long his body was in the water, although it is not an exact science.

"The important thing for me to stress is we are seeking any witnesses that have heard anything or seen anything to come forward.

"I am conscious that people may have heard rumours or speculation, and we want to hear about anything, no matter how trivial it seems."

Police want to hear from anyone who may have seen a group of people acting suspiciously in the Iffley area, between midnight last Monday and 6am on Tuesday, May 2.

Ms Trego said: "I am particularly keen to speak to anyone who saw a group of people walking near or on the towpath at Iffley.

"The towpath is used as a route home for people returning after a night out and someone may have seen something important."

Anyone with information can contact the Major Crime incident room direct on 01296 396179, Ms Trego on 08458 505505 or Crimestoppers on 0800 555111.

Police have been granted an extension on the custody time limit for the four people arrested on suspicion of murder, and can now keep them in the cells until midnight tonight.

They are two women, aged 33 and 34, and two men, aged 23 and 34. The two men arrested on suspicion of assisting offenders involved in murder were aged 43 and 20. The 43-year-old was later released on police bail.