The woman was bashed and sexually assaulted in a community garden in the Victory area of Nelson as she worked alone on Tuesday afternoon, in an attack police described as "cowardly and prolonged".
Detective Sergeant Ian Langridge said the recovering woman had been "very detailed" about the attack when interviewed by officers.
He said a large number of police continued to hunt for the "dangerous", "unpredictable" and "violent" man.
Police have released a sketch of a suspect after a lengthy interview with the woman, who was discharged from hospital today.
"She's been very detailed about what happened," Mr Langridge said.
"She's a very strong woman and she's recovering well. Obviously she's traumatised by the incident. She'll take a lot of support to get her right again."
The offender is described as either Maori or Polynesian, 170cm tall, with a short, "number 3" haircut.
He has distinctive "tribal" style tattoos, with one arm covered from the shoulder to the wrist and the other arm from the shoulder to the elbow.
Police have maintained high profile patrols of the area, and tomorrow they will have a stand at the Montgomery Square markets where people can provide information.
Forensic analysis of evidence taken by police is being treated as urgent, Mr Langridge said.
Those test results are expected by next week.
Anyone with information should call Nelson Police on 03 546 3840, the Operation Corinna free call number 0508 267 4662 or Crime Stoppers on 0800 555 111.
