Picture: Valentin Kachanov
27-year-old Valentin Kachanov was found in a river near Wouldham Road on 7 May after being missing from his home in West Thurrock since 8 February.
Further tests will now be carried out and enquiries are continuing to try and fully understand the circumstances as to how Valentin came to be in the water.
Detectives say they have found no obvious indication of any third party involvement.
A 22-year-old man from Grays was arrested on suspicion of murder but has been released under investigation while enquiries continue.