A male nurse accused of killing a colleague and raping patients after drugging them insisted yesterday that he was innocent of all charges, and told of the night Susan Annis, a fellow nurse, died.

Kevin Cobb, 38, is accused of administering the heavy sedative Midazolam to four women so he could rape or sexually assault them. Miss Annis, 31, suffered an adverse reaction and died. Two patients later insisted they had been raped by the casualty nurse while sedated.

Mr Cobb denies manslaughter, two rapes and eight charges of administering a drug with intent to commit rape or indecent assault.

The prosecution said the nurse, who worked at St Peter's Hospital, Chertsey, Surrey, spiked Miss Annis's drink intent on raping her. Yesterday Henry Grunwald QC, for the defence, told the jury: "You will have to consider whether Susan Annis could have taken the medication herself. It is not unknown for nurses and doctors to use drugs for a variety of reasons - perhaps the most simple is to enable them to get a night's sleep."

Mr Cobb, married to a GP and from Yateley, Hampshire, said he and Miss Annis had a takeaway and drinks in his room before she fell asleep. He said she went to her room, opposite his in the nursing quarters, and he checked on her later. "I opened the door and I saw Susan's feet at the end of the bed on the floor," he told the Old Bailey. "I could see Susan lying alongside the bed and I could smell vomit."

He tried to resuscitate her but could not find a strong pulse and an ambulance was called. Miss Annis died that night. Mr Cobb denied knowing she had a minor heart condition that the drug would have aggravated. The trial continues.