To friends and colleagues Colin Norris appeared a dedicated and caring nurse. He was described as a "personable, decent young man, close to his granny". But Norris harboured a more sinister side - a growing dislike of the elderly.
A clear motive for his killing spree remains unclear, although a general dislike of the elderly was mentioned as a possible factor by prosecutors.
He enjoyed a normal upbringing and came from a loving, caring and supportive family.
Norris's mother, June, and his stepfather, Raymond Morrison, live in a neat terrace in the Milton area of Glasgow.
The couple have lived there for several years, although Norris is not thought to have lived with them.
His grandmother lives in the neighbouring street. A neighbour said: "He is a personable, decent young man, close to his granny. He used to be a regular visitor."
Another neighbour added: "He was always independent. I think he went away when he was quite young to study or get a job."
He was born in Glasgow in February 1976 and raised in Partick.
Academically he was fairly average, achieving six GCSEs at school. He studied travel afterwards and then worked in travel agencies before switching careers to train as a nurse.
He has never been unemployed and always had an interest in nursing, even before college, friends said.
He studied for a Higher Nursing Diploma at Dundee University in the School of Nursing and Midwifery in Sept 1998, aged 22.
In January and September 1999 he attended lectures on diabetes and the treatment of diabetic patients with insulin. He graduated in June 2001.
While training as a nurse he worked on ward 11 at Ninewells Hospital in Dundee where he learned about the diabetic management of patients with diabetes.
In 1999 he went to ward 7 of Royal Victoria Hospital in Dundee where he cared for elderly patients. He also did placements in nursing homes.
It was while working in these institutions that his general dislike of the elderly may have begun.
When he was charged by West Yorkshire Police detectives launched an inquiry in Scotland after discovering that he trained at Dundee's Ninewells Hospital.
Police established that Norris would have had access to patients during his work placements, although there is no evidence to suggest he harmed the patients there.
In October 2001 he worked on ward 36 at the Leeds General Infirmary.
Colleagues said there was nothing to distinguish him - his only vice was popping out onto the fire escape for a cigarette during night shifts.
He was then transferred to the orthopaedic ward at St James's Hospital before Ethel Hall's death.
During police questioning in December 2002, he told officers "he seemed to have been unlucky over the last 12 months".
Police tried to jog his memory of the individual patients later. He told them he could recall Vera Wilby's distinctive hair-style but did not recall the others, even when shown photographs. When he was charged he said: "I have never done any of it."