Stepping Hill saline deaths: Police to interview 500 more
Police investigating the deaths of patients at Stockport's Stepping Hill Hospital still have about 500 people to question, they have revealed.
Charges were dropped on Friday against Rebecca Leighton, 27, a nurse who had been in custody since July, accused of contaminating saline at the hospital.
Greater Manchester Police said they were investigating 40 cases of contamination including seven deaths.
The force said officers were working "around the clock" on the inquiry.
They compared the scale of the case to the 1996 IRA Manchester bomb probe.
Assistant Chief Constable Terry Sweeney said: "This investigation is without doubt one of the most complex investigations that our most senior detectives have ever worked on, comparable in size and scope to the Manchester bomb inquiry."
Police were initially looking into the deaths of five patients at the hospital. Two were later dropped from the investigation but four more suspected victims have since been identified.
Of the seven deaths, the force said there were two confirmed cases where there was a "high probability" the deaths were caused by contaminated products.
It said the inquiry into a number of unexplained deaths at the hospital was "very much active".
Police said they had 700 people they wanted to interview, which included staff, visitors to the hospital and patients, among them potential victims. They said they had so far spoken to about 200 of them.
Mr Sweeney said: "To give some kind of understanding of the scale of this investigation, within the auspices of Greater Manchester it is one of the most complex and challenging investigations that we've faced.
"That comes about as a result of dealing with firstly an extremely difficult crime scene to manage, where we are working within the confines of a very busy hospital with many hundreds of people who come through that hospital, particularly medical staff, visitors and patients who have access in various degrees to products within the hospital."
Miss Leighton, from Heaviley, was released from HM Prison Styal, in Cheshire, on Friday afternoon after being told the charges against her, relating to the alleged tampering of saline ampoules, saline bags and medical products and theft of medication from the hospital, had been dropped.
Prosecutors said there had not been "sufficient evidence" for the case to go ahead.
Following her release, Mr Sweeney said: "At the time that Rebecca was charged there was sufficient evidence in our view, and equally importantly, the view of the Crown Prosecution Service, to bring charges around contamination and theft.
"The (reason for the) decision to discontinue is that the evidence we had at the time has not built towards the crown court phase, so that we could bring a case at this point."
The police said officers were in contact with Miss Leighton to guarantee her safety and "to try and help her back into the community".
Miss Leighton, in a statement read by her solicitor Carl Richmond, thanked her family, friends and members of the public who "never doubted my innocence during this living nightmare".
The statement said: "I've been in a living hell and was locked up in prison for something I had not done.
"It was so frustrating for me knowing that the person who actually carried out these terrible acts is still out there.
"My life has been turned upside-down. All I ever wanted to do was to pursue a profession in nursing and care for my patients."
The three patients whose deaths police are known to be investigating are Tracey Arden, 44, Arnold Lancaster, 71, and Derek Weaver, 83.
Four more suspected victims have yet to be named but their families are aware the cases have been referred to police by the coroner.
The alarm was first raised when a higher than normal number of patients were reported to have "unexplained" low blood sugar levels.
Mr Sweeney said there had been no further incidents of contamination since 16 July.
"It will take a number of weeks to complete the investigative process, the forensic process and most importantly the medical analysis which needs to take place," he added.
Ms Leighton still remains suspended from working as a nurse.
The Nursing and Midwifery Council (NMC) said an interim order suspending her from the NMC's register, imposed on 2 August, remains in place and will until further notice.
The IRA bombing of 15 June 1996 - to which police said the Stepping Hill inquiry was comparable in size - devastated the busy shopping area of Manchester city centre and left about 200 people injured.