A nurse was convicted Monday of killing four elderly patients with insulin overdoses in English hospitals in 2002.

Colin Norris, 32, was also convicted of attempting to kill a fifth patient. He will be sentenced Tuesday.

Police began investigating following the death of Ethel Hall, 86, at Leeds General Infirmary in November 2002. She was found to have 12 times the normal level of insulin in her blood.

Police expanded their investigation after checking records at the infirmary and St. James's Hospital, where Norris also had worked.

He was also convicted of killing Doris Ludlam, 80, Bridget Bourke, 88, and Irene Crookes, 79, and of attempting to kill Vera Wilby, 90.

Norris was arrested on Dec. 11, 2002, but not charged until Oct. 12, 2005.

Prosecutor Robert Smith said all five victims had undergone surgery for hip fractures, were in poor health and could be regarded as a "burden to nursing staff."

While training, Smith said Norris had said he did not like looking after "geriatric patients."