The body of heroin addict Rachel Whitear is to be exhumed as part of the reinvestigation into her death.
Pictures of Rachel's body were used in an anti-drugs campaign
A photo of the 21-year-old's dead body showing her crouching face down with a syringe in her hand was released as a warning of the dangers of drugs.
Her death in Exmouth, Devon, four years ago was presumed to be an overdose, but no post-mortem examination was done.
A blood test later revealed there was not enough heroin in the student's blood to kill her.
The coroner recorded an open verdict into her death.
Detective Chief Superintendent Paul Howlett, head of CID at Wiltshire Police, confirmed the decision to dig up Ms Whitear's grave on Friday.
He was joined by her mother and stepfather, Pauline and Mick Holcroft, at a news conference at Hereford racecourse.
Reading from a statement, Mr Holcroft said: "This has obviously been a very difficult few years for Pauline, myself and our family, culminating in today's announcement.
"Nothing can prepare a family for this.
"Although we are enormously saddened, we are coming to terms with the fact that an exhumation of Rachel's body is necessary."
The couple, from Withington in Herefordshire, have been critical of the Devon and Cornwall Police investigation into their daughter's death.
Wiltshire Police took over the inquiry after it was voluntarily referred to the Police Complaints Authority.
As part of their investigation, two officers flew to Greece to speak to Ms Whitear's drugs counsellor, one of the last people to see her alive.
Asked for her reaction to the decision to exhume her daughter's body, Mrs Holcroft replied: "It is very upsetting.
"All we really want is a closure on it, but we know that may never happen.
"This is an opportunity to find out. It is difficult to live not knowing or understanding what your daughter died from."
Mr Holcroft added: "In the search for the truth, it is absolutely necessary."
Mr Howlett said he was unable to give a cause of death with any certainty because a post mortem examination had not been carried out.
Heroin in syringe
A forensic medical expert has now said that carrying out such a procedure could help to give a cause of death, despite the passage of time.
Asked if there was heroin in the syringe she was clutching when her body was discovered, he said: "I think it is inconclusive at this time."
Two men from the Midlands were arrested in connection with Ms Whitear's death last year.
The PCA confirmed in October that neither would face any charges.
No date has been set for the exhumation of Ms Whitear's body, which is buried at St Peter's church in Withington.