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.

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.

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.

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

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.

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.

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.

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.

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.

The case of care worker Bunthawee Rimmer, who enjoyed a comfortable lifestyle as a live-in carer to Paul Norfolk. When she was made the main beneficiary in Paul's will, Rimmer stood to inherit almost £350,000 and resorted to a hammer attack to ensure he would not change his mind.

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 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.

The case of New York paramedic Paul Novak, who boasted of committing the perfect murder after the dust had settled on the death of his first wife Catherine.

The case of carer Thomas Dunkley, who aided boxer Shaun 'The Guv'nor' Cummins after he became paralysed, and later killed and dismembered his patient.

The story of debt-ridden mother-of-three and night-time sex worker Beverley James. By day, she was meant to care for Harriet Davison, a frail woman she beat to death.

The murder of politician Kathy Augustine, who died after being given paralysing drug succinylcholine by her husband Chaz Higgs, a professional nurse.

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.