A new Amazon Prime documentary on the crimes of the 'Teacup Poisoner' Graham Young, who murdered two people in Hertfordshire, has been released.

Murder in a Teacup was released by the popular streaming service February 19, and focuses on the murders committed by serial killer Young at the John Hadland Laboratories in Bovingdon in 1971.

He murdered 59-year-old Bob Egle, a storeroom manager at Hadland, and Fred Biggs, a 56-year-old local councillor and part-time employee by poisoning their tea.

After suspicions about Young began to rise, he was 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.

READ MORE: The hideous murders of the St Albans Poisoner Graham Young

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

Murder in a Teacup sees Ivo Graham voice Young, and features interviews from those that were there at the time of his crimes and experts in the field.

It also discusses Young's third victim, his stepmother, who he poisoned when he was just 15, his concerning childhood fascinations including poison, black magic and the Nazis.

You can stream Murder in a Teacup on Amazon Prime now.