PRESS ASSOCIATION -- Police are continuing to hunt the person behind the deliberate contamination of saline solution at a hospital, following the deaths of three patients.
Security has been stepped up at Stepping Hill Hospital in Stockport while the probe continues.
The deaths of a 44-year-old woman and two men aged 71 and 84 remain unexplained, while a further 11 patients have been affected but not seriously harmed. Police said it was clear that someone had been tampering with vials of saline and they needed to be caught.
Describing it as a "fast-moving investigation", Assistant Chief Constable Terry Sweeney said: "We have someone deliberately contaminating saline in the one place that people should feel they are being most cared for. I want to reassure everyone connected to the hospital - staff, patients, visitors and the wider community - that we are determined to prevent further harm and to bring the offender to justice. We are working very closely with the hospital to improve the security of the patients and staff at the hospital."
As well as increased security patrols, he said he would also suggest to health trust bosses that anyone entering the hospital should be searched beforehand.
Mr Sweeney said it would be speculation to say the offender was a member of staff but he said all medical professionals at the hospital as well as patients would be spoken to in the next 24 hours.
The hospital contacted police on Tuesday after an experienced nurse reported a higher than normal number of patients on her ward with "unexplained" low blood sugar levels. It concluded that some saline ampoules had been "interfered with" - with the contamination thought to have involved the use of insulin.
All future deaths at the hospital that show any signs of relevant symptoms will be passed to South Manchester Coroner John Pollard for the foreseeable future and may be referred to detectives to investigate.
A spokesman for Stockport NHS Foundation Trust said it had yet to formally receive a request from Greater Manchester Police to introduce security checks.
The trust's chief executive, Dr Chris Burke, said: "It was the staff at the hospital who brought this matter to our attention and I've asked them to continue to be extra vigilant to help safeguard patients. We have increased security both in terms of access to the hospital and access to medicines and already replaced all saline ampoules across the hospital. We are doing all we can to protect our patients and ensure their safety while under our care."