Video report by ITV News Correspondent Dan Rivers
Police have opened a fresh criminal investigation into the deaths of hundreds of patients who died at the Gosport War Memorial Hospital in Hampshire.
A report last June found there were more than 450 patients who may have been given unnecessary doses of opiate painkillers between 1989 and 2001.
Families of the victims have been fighting for more than 20 years in the hope an investigation may bring about criminal charges.
This is the fourth such investigation into the deaths, following the failure of the previous three.
Dan Rivers said there was a mixed response to a new police investigation from families
In a statement, Assistant Chief Constable Nick Downing, representing the Eastern Policing Region, said: "The family of those affected by the events at Gosport War Memorial Hospital are at the heart of everything we do, and I hope the news that we will not be carrying out a full investigation is of some comfort to them.
"This investigation is not about numbers, it is about people - specifically those who died at the hospital and the loved ones they have left behind.
"There have been three previous police investigations into deaths at the hospital.
"It was therefore important for us to carry out an initial assessment of the materials obtained by the Gosport Independent Panel to establish if it contained sufficient new information tat has not already been submitted to the Crown Prosecution Service."
An investigation in 2018 found there was an "institutionalised regime" of prescribing the drugs without medicals justification.
This pattern of behaviour continued despite concerns being raised by nurses between 1991 and 1992.
The report adds at least another 200 patients "probably" also had their lives cut short, when missing records are taken into account.
An independent panel found Dr Jane Barton, who has since retired, was "responsible for the practice of prescribing" at the wards over a 12-year period, where she served as a clinical assistant.
Police will now meet with families on a one-to-one basis and invite them to give statements on their experience with the hospital.
Speaking on Tuesday, assistant chief constable Nick Downing, who is leading the investigation, said it would take up to nine months to determine whether anyone may or may not be charged.
"Our investigation at this stage does not involve suspect... We are here to prove that causation link first and foremost.
"We estimate that will take a minimum of nine months. For the families that's unacceptable. And I see that. But that challenge is we don't want to rush what we're doing."
'I will continue my fight for justice'
Majorie Bulbeck's mother, Dulcie, was admitted for rehabilitation following a stroke in 2001, but her condition deteriorated rapidly while in Dr Barton's care and she died shortly after.
Majorie has been fighting for justice for 18 years and today's decision to re-open a fresh investigation has been welcomed.
Ms Bulbeck said she has not received an apology from Dr Barton, who was responsible for administering drugs at the hospital.
Speaking to ITV News, Ms Bulbeck said: "I don't really know what she thought she was doing.
"Whether that was just moving people on or making beds to make enough room for the next lot, I don't know.
"It certaintly wasn't the correct thing that she should have been doing as a doctor and someone in the so-called healthcare profession.
"The police should have taken the complaints seriously when they first started."
She added: "I had apologies from all these differentd epartments so if they're apologising, I need to know what they're apologising for".
Ms Bulbeck, who has fought since her mother's death for the truth, said there "must have been a cover-up".
"Those amount of people could not have died in that amount of time. It's a ridiculous amount," she said. "They were supposed to be looked after by the caring profession.
"What's happened to the caring profession, I don't know, because it doesn't seem to be there."
Timeline of events in the Gosport War Memorial Hospital scandal:
August 1998 - Gladys Richards dies in Gosport War Memorial Hospital after going in for rehab following a hip operation. Her family report concerns about her treatment to the police and the coroner.
2001 - In the three years after Mrs Richards' family came forward, three more went to police and two more case were reported to the NHS ombudsman.
July 2002 - The Commission for Health Improvement (CHI) criticised Portsmouth Healthcare NHS Trust, which ran the hospital, for excessive use of pain relief and sedative drugs.
February 2005 - Hampshire Police detectives pass files of evidence to the Crown Prosecution Service (CPS) about the deaths of elderly patients.
December 2006 - Hampshire Police announces no-one would face prosecution over the deaths after a four-year inquiry. The CPS says that negligence could not be proven to a criminal standard and that there was no realistic prospect of conviction of healthcare staff.
April 2009 - An inquest jury rules drugs given to five elderly people at the hospital contributed to their deaths.
January 2010 - The General Medical Council finds Dr Jane Barton guilty of serious professional misconduct. A panel found she made a catalogue of failings, including issuing drugs which were "excessive, inappropriate and potentially hazardous". She was not struck off.
March 2010 - Dr Barton retires from medical practice.
August 2010 - The CPS announces no criminal charges will be brought against Dr Barton after finding insufficient evidence to mount a prosecution for gross negligence manslaughter in 10 key cases.
April 2013 - A coroner rules that medication given to Mrs Richards contributed "more than insignificantly" to her death.
July 2014 - An independent investigation into more than 90 deaths at the hospital is launched by health minister Norman Lamb.
June 20 2018 - The inquiry is published.
April 30 2019 - Police announce full criminal investigation.