Police initially treated the death of Beth Aspey, 34, as “unexplained” after she was found dead in a block of flats.
But a murder investigation was launched after the post mortem revealed the cause of death as blunt force injuries.
A 44-year-old man was arrested on Friday on suspicion of murder with detectives being granted extra time to question him in custody.
The victim’s family are being supported by specially trained officers and have asked that their privacy is respected.
Thames Valley Police stepped up patrols after Ms Aspey was found in Laud Close at about 4.30pm on Friday.
Det Insp Dejan Avramovic, said: “Our officers have been carrying out a thorough investigation in the days since this incident was first reported to us, and now, following the results of yesterday’s post mortem, we have started a formal murder investigation.
“I understand that this will cause some concern in the community, however, I would like to take this opportunity to reassure people that this is an isolated incident and that a man has been arrested in connection with it.
“Members of the public will have seen an increased police presence in the area since Friday and this will remain in place while our investigation continues. If you have any questions or concerns at all, please feel free to approach our officers.
“Finally, if you have any information at all which you think could help our investigation, then please call us on 101, quoting reference number 43210184533.
“We are particularly interested in speaking to anyone who saw or who had contact with Beth on Friday 30 April. We are releasing a photograph of her in order to help with this part of our investigation.”
Alternatively, you can contact Crimestoppers anonymously on 0800 555 111, or make a report online.