Police investigating the death of three patients at Stepping Hill Hospital have made an arrest. Three people died and another 16 were affected by contamination of saline solution drips at the Stockport hospital last summer. BBC correspondent Nick Ravenscroft said he understood the arrested person was a male nurse in his 40s. Criminal charges against nurse Rebecca Leighton were dropped in September because of insufficient evidence. Tracey Arden, 44, Arnold Lancaster, 71, and 83-year-old Derek Weaver all died after insulin was administered unlawfully, police said. Tests are still going on to decide whether the poisoning contributed to their deaths. Officers were first called to the hospital on 12 July after an experienced nurse reported a higher than normal number of patients had \"unexplained\" low blood levels. Ms Leighton was initially charged with criminal damage with intent to endanger life and theft. She was sacked by Stockport NHS Foundation Trust after admitting stealing opiate drugs. She is appealing against the decision.