A 46-year-old nurse suspected of murdering three patients at Stepping Hill Hospital has been released on police bail pending further inquiries.
Victorino Chua was arrested on Thursday on suspicion of tampering with medical records at the hospital in Stockport, Cheshire, and was further arrested on suspicion of three counts of murder and 18 counts of causing grievous bodily harm.
Chua, from Heaton Norris, Stockport, has now been released on bail until an unconfirmed date in April pending further inquiries, Greater Manchester Police have confirmed.
Chua was being questioned over the contamination of saline drips in June and July last year, causing patients' blood sugar to fall in "hypoglycaemic episodes."
Tracey Arden, Arnold Lancaster and Derek Weaver died shortly after experiencing such episodes. Police are also investigating the death William Dickson, 82, who died on New Year's Eve and is also believed to have had his saline drip poisoned.
"The public perception is that, in most cases, once a person is arrested they are subsequently charged," said Assistant Chief Constable Terry Sweeney.
"The reality is very different and it is not unusual for someone arrested for an offence - whatever that might be - to be bailed in order for officers to carry out further inquiries.
"I want to reiterate what we have said from the outset: that this is an extremely complex investigation that requires very detailed forensic and medical analysis. These inquiries must be done thoroughly, carefully and with integrity and cannot be rushed.
"It is also important to reiterate that we are continuing to follow the evidence in our search for the truth and cannot rule out making more arrests further down the line. This man has been bailed in order for us to continue with our work and it is vital that the public, and in particular the media, do not jump to conclusions or second guess what the outcome of this man's arrest or our wider investigation will be."