On June 29, 1972, Graham Young stood in the dock at St Albans Crown Court, and was sentenced to life imprisonment for the murder of two people, and the attempted murder of more.

The crimes of the Teacup Poisoner are among the worst in modern British history, and they took place right in the middle of sleepy Hertfordshire.

Early years

Young was born on September 7, 1947, but after his mother's death when he was just 14 weeks old, his aunt and uncle would care for him until his father remarried, reuniting the family.

As with most serial killers, he displayed concerning interests during his childhood, becoming fascinated by poison, black magic and the Nazis while still at school, and this quickly escalated as his crimes began.

First crimes and Broadmoor

In 1961, aged just 14, he poisoned his stepmother and sister, with Young's father confronting him after his sibling was hospitalised. But, nothing incriminating was found, and he warned him to be more careful when "messing about with those bloody chemicals".

On April 21, 1962, Young's stepmother died, with her death attributed to a prolapsed cervical disc from a car accident, but Young later told police that he poisoned her with a lethal dose of thallium.

Get more stories like this delivered to your inbox every week by signing up to the Herts Ad In Brief newsletter.

At her wake, he poisoned a relative. His father then also became ill, with doctors telling him he was just one dose away from death.

By now, he had established his trusted method of slipping the poison into people's teas, which earned him his nickname.

But, suspicions were now arising that Young was behind the poisoning, with his school setting up an interview with a psychiatrist, posing as a careers advisor, who contacted police when he revealed extensive knowledge of poisons and toxicology.

He was arrested and confessed to poisoning his father, stepmother, sister and a school friend. Psychiatrist Dr Christopher Fysh testified that Young had a psychopathic disorder, and recommended he be sent to Broadmoor, where he was one of the hospital's youngest ever in-mates.

Dr Fysh recounted that Young told him "I am missing my antimony, I miss the power it gives me", and despite some suspicious poisoning activity during his stay at Broadmoor, it was never proved he was behind it.

Release and first murder

After seeing his 1965 application for release rejected, with his father demanding he never be released, Young finally got his way in 1970, even though he had told a nurse: "When I get out, I'm going to kill one person for every year I've spent in this place."

He was out by 1971, living with his sister and her husband in Hemel Hempstead. His poisining efforts quickly resumed, purchasing antimony and thallium from a London chemist.

In February that year, he poisoned Trevor Sparkes while on a storekeeping training course in Slough, but no cause for his victims violent illness was found and he survived after months of recovery.

He would then get a job as assistant storekeeper at John Hadland Laboratories in Bovingdon, a company that manufactured thallium bromide-iodide infrared lenses, which were used in military equipment, but thankfully, no thallium was stored on site.

In July 1971, Young would commit his first murder, poisoning 59-year-old Bob Egle, a storeroom manager at Hadland and his immediate superior. Initially, Egle's death was recorded as a rare form of Guillain–Barré syndrome and not poisoning.

He would also poison factory employees Ron Hewitt, Diana Smart, David Tilson and Jethro Batt, using his tried and tested method of slipping it into their tea, but they all survived.

Second murder

Fred Biggs, a 56-year-old local councillor and part-time employee at Hadland, would not be so lucky.

By this time, the virus-like symptoms people were exhibiting was known as the "Bovingdon Bug", and Biggs, who had both antimony and thallium slipped into his tea, was next to be struck down.

READ MORE: Alec Housden pleads not guilty to Harpenden sexual offences

He died on November 19, 1971, but suspicions about Young, who never caught the "Bovingdon Bug" despite his close proximity to all the victims, were on the rise.

Word also spread about his interest in poisons after he was questioned by Hadland's medical officer, Dr Iain Anderson.

Arrest and sentencing

The police were contacted and Young was arrested on November 20, 1971, asking "which one is it you're doing me for?" as he was led away.

Officers found poisons in his bedsit as well a rather incriminating diary in which he noted the doses given to his victims, their effects, and whether he was going to allow each person to live or die.

Young confessed to poisoning Egle, Biggs, Batt, Tilson and Sparkes, while also boasting he had committed the "perfect murder" when killing his stepmother.

When asked why he'd done it, he coldly replied: "I suppose I had ceased to see them as a people - at least, a part of me had. They were simply guinea pigs."

On June 29, 1972, after one hour and 38 minutes of deliberation, the jury found Young guilty. A life sentence was passed down, and he would die in his HM Prison Parkhurst cell in 1990, aged 42.