Officers from Thames Valley Police have released CCTV images of the woman who is believed to have been discovered in Cresswell Lake between the A40 and A34 near Yarnton.
The woman, believed to be in her mid-20s, was found just before 8.30pm last Monday after officers were called to reports of a body being located in Cresswell Lake.
Investigating officers said they believed the same woman was knocking on doors in the area asking for a shower before her death.
Police said the woman’s post-mortem examination couldn’t ascertain the cause of her death.
They described the woman as having shoulder-length dark hair, light skin, of slim to medium build and approximately 5ft 6ins tall.
She was wearing an olive green Barbour jacket, a burnt orange jumper and orange/red and cream striped long-sleeved t-shirt and fitted blue jeans.
Detective Inspector Tracey Benham, based at Banbury police station, said: “We are still treating the death of the woman as unexplained, but as yet, we have been unable to ascertain her identity.
“Despite extensive investigations, we have exhausted lines of enquiry as to identifying the woman, and so we are taking the decision to release these CCTV images, captured on 8 August, as we have ascertained that this is very sadly the woman who was located in the water.
“This is a tragic incident and we are determined to find out who the deceased person is and are leaving no stone unturned in our efforts to identify her and notify her next of kin.
“I would again ask anybody who was aware of a woman matching the description given in the area over the last few weeks, or knows the identity of the woman seen in this CCTV image, to please get in touch.
“Any information that you may have that could assist this investigation will be gratefully received and will hopefully allow us to locate the woman’s family and offer the support that they will need following this tragic incident.”
Police are asking anybody with any information, no matter how insignificant you believe this may be, to contact 101, or make a report online quoting incident reference 2048 (16/8).