BBC drama Four Lives documents the devastating murders of four young men at the hands of evil serial killer Stephen Port.
Port is currently serving a life sentence in the high-security Belmarsh prison after his tragic murdering spree in 2014, which saw him kill four young men - Anthony Walgate, 23, Gabriel Kovari, 22, Daniel Whitworth, 21, and Jack Taylor, 25.
At his 2016 trial at the Old Bailey, the jury were told of how Port had asked the four men to his home separately before giving them fatal doses of GHB - known as the "date rape" drug - before raping them and killing them.
The new three-part drama also covers the police's incompetence in the investigations of the murders.
Serial killer Port is played by actor and comedian Stephen Merchant, who is best known for co-creating sitcom The Office. Merchant previously criticised the police for their handling of the case.
"When I first read the script I wanted to believe some of the many police errors in the investigation must have been overstated for dramatic purposes, but they weren't," he said before the show began airing.
The four tragic victims' final moments are portrayed in the three-part drama.
Anthony Walgate, 23, was Port's first victim. He was from Hull and had been studying fashion in London. He was asked to Port's flat in Barking under an alias, where he was tragically killed.
Port then dumped Walgate's body outside the flat and later called the police himself to say he found an unknown man outside his apartment block. It was only later he admitted he had dumped the body after the pair met up for sex.
Sarah Sak, played by Sheridan Smith, is Anthony's mother. She tirelessly fought for justice for her son and the other victims of Port's devastating murdering spree.
Sak has claimed the police could have prevented the other men's deaths if they had investigated her son's case properly. The police at the time told Sak her son's death wasn't suspicious - but she suspected it was and continued to fight.
Gabriel Kovari - originally from Slovakia - was Port's second victim. Kovari was tragically found slumped in a graveyard in August 2014, but the police didn't rule the death as suspicious. This meant that it was not subjected to forensic post-mortem examination.
Kovari's friends also tried to give their information on what happened but they claimed they were completely ignored by the police, and they say Port would have been caught quicker with their evidence.
Daniel Whitworth was the third young man to be killed by Port. He was Port's youngest victim at just 21-years-old and he was found at a graveyard with a note in his hand.
The note claimed Whitworth had killed Kovari with an accidental overdose of GHB a few weeks previously and couldn't live with what happened. The police alleged that Whitworth's family confirmed it was his handwriting, but an inquest was told that the family never confirmed the handwriting belonged to their son.
Jack Taylor was Port's fourth and final victim. He was from Essex and he was found in similar circumstances to the other victims. He had been given a fatal dose of GHB and was found dead near Port's home.
Police said at the time that Taylor's death was not suspicious and that they believed he was just a victim of a drug overdose.
Donna Taylor is Jack's sister, played by Jaime Winstone in the BBC drama. Donna and Jaime have since formed a close bond.
"I met up with Jaime on a few occasions with my sister Jen and the actress Stephanie Hyam who plays her," she told The Sunday People, "That first meeting was quite emotional. Once we got to telling them about what we’d been through all four of us were in tears. The only thing I told her I wanted was for it to be truthful."
