Suspicions were raised when Norris predicted that healthy Ethel Hall would die at 5:15 am one night, which is when she fell into a catastrophic arrest, and tests revealed that she had been injected with an extremely high level of man-made insulin.

Doubts were later raised about his conviction by, among others, Professor Vincent Marks, an expert on insulin poisoning, who concluded from his own studies that there was a 1 in 10 chance that each patient's arrest could have happened naturally.

[6] Learning about McTavish would later be regarded as a likely inspiration for Norris, and he would have believed at this point that insulin would be the "perfect" weapon for murder as it leaves the blood very quickly.

[6] Norris began working in Leeds after qualifying in June 2001, but quickly fell out with experienced authority figures, finding it difficult to be told 'no' or what to do.

[12] In the month in which he began killing patients with overdoses, Geen appeared in an edition of the Banbury Citizen which featured an interview with Leskovac.

[19] An anonymous male nurse called Hall's son from the hospital at 5:30 a.m. that morning telling him that she had taken a "turn for the worse", and it was not established who this man was.

[1][18] The doctor who had ordered the tests was a diabetes expert who specialised in insulin and hypoglycaemic episodes, and she had believed the incident to be suspicious.

[32] They began in May 2002, which also notably happened to be when the detailed probationary monitoring of Norris's early progress as a newly qualified nurse ended.

[7] 88-year-old Bridget Bourke, who had been admitted to the ward on 16 June also with a broken hip, was then discovered at 3:10 a.m. on 21 July (by Norris) suffering from a hypoglycaemic attack; she died the next day.

[9][41] After he was first arrested, Norris immediately left Leeds and went back to Scotland, before then leaving the UK eight times to go abroad, including to Tenerife for a six-month holiday.

[41][42] After his conviction his partner recounted an incident around this time when Norris became violent and drunk, and wouldn't stop crying because he said he was scared of going to prison.

[23] The police were dismissive of Norris's claim that an intruder must have come in during the nightshift through the fire escape while nurses were having a cigarette before injecting Hall.

[14] Throughout the interviews he acted notably aggressively and arrogantly, challenging detectives, and became physically angry at times to the point where he had to be restrained.

[1] Criminologist Jane Monkton-Smith said it was particularly unusual that Norris didn't behave as if he wanted to defend himself in interviews, but instead challenged the police and acted evasively.

[44] Chief superintendent on the case Chris Gregg, holder of the Queen's Police Medal and who caught David Bieber, 'Wearside Jack' and the killer of Leanne Tiernan, said that Norris's prediction of Hall's illness showed that it wasn't just a spontaneous incident where a criminal nurse at work had, for whatever reason decided to kill someone, saying "he actually premeditated this, hours before".

[49] Norris claimed, despite the blood test evidence, that none of the patients had been injected and if they were then an 'intruder' must have done it (since records showed no other staff member could have been responsible).

[50] Norris had acted particularly aggressively throughout the trial, banging on the windows of the judge and attacking members of the press when departing the court, shoving two against a wall.

[42] Referred to in the British press as the "Angel of Death", Norris was convicted of killing his victims by injecting them with high levels of insulin.

[52] Ludlam was a mother of two, a grandmother and great-grandmother who had worked as a nursery school teacher and fostered children for the charity Barnardo's.

"[11][13][19] After the verdict was announced, Leeds Teaching Hospitals NHS Trust apologised to the victims' families for Norris's "disturbing" crimes, subsequently describing him as an "extremely dangerous criminal".

[57] Norris had also been arrested for another death of a patient, but the Crown Prosecution Service decided not to charge him in this case because of "complicating factors".

[7][60][3][61] Norris was tasked with "reviewing" her conduct, and in doing so, he would have learned that insulin is the perfect weapon for murder because it leaves the blood very quickly.

[51] Chris Gregg said that he believed that Norris decided to poison the women simply because he found elderly patients irritating.

[64] High-profile criminologist David Wilson commented on the case of Norris and other recently convicted serial killers by saying: "What's happening at the moment is that new groups are emerging as being vulnerable to attack".

[68] Norris's defence team had argued that the deaths could have been the result of 'naturally' raised insulin levels caused by severe spontaneous hypoglycaemia, but the judges rejected this possibility.

[69] The inquiry recommended the introduction of 'student practice passports', which would report on the personality and integrity of students while they trained as medical professionals at university.

[69] It was felt that this may have flagged up Norris as an issue earlier had they been in use at the time of his studying, since he had knowingly acted aggressively during placements, had a poor absence record and had clashed with tutors on numerous occasions.

[69] Nurse managers had already been urged after Norris's conviction in 2008 to take greater care when recruiting staff, and NHS employers had introduced new guidance on pre-employment checks.

[37] On 4 October 2011 the BBC reported that retired Professor Vincent Marks – a leading expert on insulin poisoning – was concerned about Norris's conviction.

[70] He claimed the jury at Norris's trial was wrongly led to believe by experts that a cluster of hypoglycaemic episodes, among people who were not diabetic, was sinister.