When an autopsy revealed high levels of insulin in Eric Lloyd's body, police realised his widow, nurse Marie Whiston, had been using her medical skills not to care but to kill.

When Alice Grant died it was sad, but not unexpected. The 84-year-old needed round-the-clock care from her nurse Alison Firth. What nobody expected was how much Firth would resent the extra care her vulnerable patient required, or what lengths the lazy nurse would go to in order to avoid the work.

The case of care home worker Karen Pedley, who was given 14 life sentences in 2016 and found guilty of killing a 96-year-old resident by setting fire to her room.

Care worker Thelma Purchase plotted with her son and a friend to murder disabled Greg Baker who Purchase once worked for. She knew he couldn't defend himself and she stood to be a beneficiary in his will.

The series begins by examining the case of Allitt, a nurse on the children's ward of a hospital in Lincolnshire. She poisoned a string of young patients under her care over the course of 59 days in 1991, murdering four.

Benjamin Geen worked as a nurse at Horton General Hospital in Banbury, Oxfordshire. In 2006 he was tried and convicted of murdering two patients and causing GBH to 15 others but has always maintained his innocence.

Genene Jones worked in the paediatric intensive care unit of a Texas hospital.

Police were called in after a suspicious number of patients died while in Daniela Poggiali's care.

The chilling story of German nurse Stephan Letter, who was tried for the murders of 29 patients at a clinic in the Bavarian town of Sonthofen.

Dialysis nurse Kimberley Clark Saenz poisoned patients by injecting bleach into their bloodstream.

Real crime. Chilling series looking at nurses who kill their patients. Niels H adminstered lethal doses of drugs to patients in order to later 'show off' his resuscitation skills.

Real crime. Chilling series looking at nurses who kill their patients. Colin Norris targeted elderly patients by adminstering them unnecessary doses of insulin.

The case of Filipino nurse Victorino Chua, who secured a job at Stepping Hill Hospital, Manchester, and began to inject insulin into saline bags of 44-year-old Tracy Warden and 83-year-old Alfred Weaver.

Charles Cullen was a nurse that is believed to have killed over 300 patients. Experts analyse the actions and motive of this insidious serial killer.

Nurse Malcolm Webster was convicted for the murder of his first wife, Claire Morris. For 17 years it was believed to be an accident; until he staged another 'road accident' in New Zealand, involving his second wife, Felicity Drumm.

Anne Grigg-Booth, who was responsible for administering painkilling injections to patients, was a heavy drinker with a passion for drugs. We hear from the doctor that Grigg-Booth's team lined up as an expert witness in her defence. He was never to be called; Nurse Grigg-Booth killed herself.

Efren Saldivar confessed to killing 40 to 50 patients over an eight-year period. Quickly christened an "Angel of Death," he targeted patients who were already near death. Statistical analysis indicates that the total number of murders committed by Saldivar could be as high as 200, but the bodies were cremated after death long before he owned up to his deeds on the wards.

Megan Haines, South African immigrant and mother of a dangerous and disaffected son, carries out a murderous rampage against the elderly in the quiet coastal town of Ballina, New South Wales.

Jeannie Miata was convicted of murdering a 68-year-old Texas woman with a lethal dose of insulin in 2002. Inside prison, journalist Carolyn Canville asks her why she did it.

On November 18, 2011, Roger Dean, a nurse at Quakers Hill Nursing Home in Sydney, Australia murdered 11 elderly residents after setting fire to the facility as they slept in a bid to hide evidence of his theft of painkillers.

Vickie Dawn Jackson was described as sweet and 'gone to fat' by locals in her small Texas town. Why did Vickie kill off the friends and relatives of those whom she knew in Nocona, Texas? Texas journalist Skip Hollandsworth spent time with Nurse Jackson at her Texas jail and reveals the truth about a remarkable, and evil, woman.

Gary Davis told his Facebook friends that 'I hate old people' and days before two patients in his care were found dead, he predicted they would die. Those facts were enough to put him in the frame as a doctor became convinced that foul play was responsible for their. Rob Kaplan, a Forensic Psychiatrist from a Sydney University offers a unique insight into health serial-killers.

Wettlaufer, 49, of Ontario, intentionally administered fatal doses of drugs to her victims, aged 75 to 96, between 2007 and 2014. After killing, she would post some of her dozens of verses. Wettlaufer's victims included five women and three men - all of whom were patients at Caressant Care nursing homes in Ontario, where Wettlaufer had worked.

'Angel of Death' Donald Harvey is believed to have murdered nearly 60 patients, often by administering arsenic and cyanide, in a 20-year killing spree.

The story of Sandra Weir, who acted as a carer for her elderly neighbour. But she was stealing from the pensioner to fund her drug addiction, leading to a tragic confrontation.