British police arrested a nurse on murder charges Wednesday after three patients at the hospital where she works received saline contaminated with insulin and died.
Greater Manchester Police said they detained a 27-year-old woman. The Nursing and Midwifery Council identified her as Rebecca Leighton, a registered nurse. It said she would be suspended "as quickly as possible."
Crime scene investigators were searching her apartment.
The contamination was discovered last week after a nurse at Stepping Hill Hospital in Stockport, northwest England, reported a higher-than-normal number of patients with unexplained low blood sugar levels.
Investigators are conducting tests to find out whether the deaths of a 44-year-old woman and two men aged 71 and 84 were caused by the sabotage. A fourth man is in critical condition, and 10 other patients fell ill but recovered.
Security has been stepped up at the hospital, 150 miles (250 kilometers) northwest of London.