The body of the 45-year-old, who has two daughters, was discovered by a man walking his dog in Little Heath in the east London town, according to police.
The Metropolitan Police said preliminary findings from a post-mortem examination gave the cause of death as neck compression and possible blunt force head trauma.
Police said homicide detectives are investigating the case.
There had been no arrests as of Friday morning.
Ms Rawlings, who lived in the Chelmsford area in Essex, had visited Kings Georges Hospital in Ilford, east London, on Monday evening.
After leaving the hospital, she made her way on foot to Barley Lane in the direction of the A12.
Police said they believe someone may have approached Ms Rawlings while she was walking on this road.
Her body was found the next day in shrubbery in Little Heath and reported to the police around 2pm.
Detective Chief Inspector David Hillier, who is leading the investigation, said: “My team and I are working around the clock, following a number of enquiries in our work to establish what happened to Maria.
“Her family are understandably distraught and we are doing all we can to help them as they begin to come to terms with their loss.”
In an appeal to the public, he said: “I want to hear from anyone who knew Maria and knows about where she had been and who she had been associating with. Have you seen her in the area in the company of another person? Had you recently heard or seen a disturbance or struggle in the area but did not think it significant at the time?”
He said residents in the area may have dash cam or doorbell footage that could have captured her and to get in touch with police if they can help.
Chief Superintendent Stephen Clayman, Basic CommandUnit Commander for Barking and Dagenham, Havering and Redbridge, said: “I understand the concerns around safety that will arise from this, particularly from women, and we have increased patrols in the area from our local policing teams.”
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