A fourth arrest has been made in the Jasmine Wilson homicide investigation - but her grieving mother is pleading for anyone who knows the killer to come forward.

Police say a 47-year-old woman has been charged with perverting the course of justice and will appear in the Whanganui District Court on Tuesday, September 10.

Wilson, 30, died in Wellington Hospital on August 2, two days after she was taken to Whanganui Hospital in a critical condition with non-accidental injuries.

A 28-year-old man has been charged with injuring with intent to do grievous bodily harm and assault with intent to injure. Two other people - a 48-year-old man and a 27-year-old woman - have been charged with perverting the course of justice.

Advertisement

Police continue to appeal for anyone with information about Wilson's death to come forward.

No one has yet been charged with murder.

Wilson's mother is urging anyone with information about her daughter's death to come forward.

Brenda Reuben told the Whanganui Chronicle her family was grieving and desperately seeking closure.

"We know Jasmine was dropped at Whanganui Hospital with the severe injuries that led to her death, but we still don't know how she sustained those injuries," Reuben said.

"No one should have to see a family member in the state we saw Jasmine in. She was unrecognisable."

Following Wilson's death, police launched a homicide investigation during which they seized a white Toyota Carib station wagon registration number ABQ682.

Their investigation of this vehicle has now been completed following the scene examinations at two properties in Millward St and Karaka St.

Advertisement

Reuben said that her daughter was a loved mother, daughter, sister and granddaughter.

"There are people who know what happened to her. We are pleading with you to come forward and do the right thing," she said.

"Anyone who has information, no matter how small you think it might be, please get in touch with police."

Anyone who can help is urged to call Police on 105, or give information anonymously by calling Crimestoppers on 0800 555 111.