Police were yesterday given more time to question a male nurse suspected of murdering three hospital patients.
Victorino Chua (46), was arrested on Thursday on suspicion of tampering with medical records at Stepping Hill Hospital in Stockport, Cheshire.
Detectives are probing the poisoning of patients at the hospital last summer.
Greater Manchester Police said the nurse was now being questioned on suspicion of three counts of murder and 18 counts of causing grievous bodily harm.
Yesterday they were given another 24 hours to question Chua.
Detectives have obtained a further warrant of detention that is due to expire at 10.10am today.
Assistant Chief Constable Terry Sweeney said last night: "This specific inquiry, and the investigation as a whole, is a difficult and complex piece of work that requires very detailed forensic and medical analysis, which is ongoing."