It dealt with the events between the Wests' arrests in February 1994 and Fred's suicide in Birmingham's Winson Green Prison on New Year's Day 1995.
She attends a police interview with Fred West, who confesses to killing his daughter, Heather, in 1987 and burying her in his back garden.
After the police find the remains of several women buried at the West home, Fred says that one of them is a lodger, Shirley Robinson, killed in 1978 when she was pregnant with his child.
DSI John Bennett is concerned that Fred's confession might have been made under duress or fabricated to impress Janet, and warns her not to get too close to him.
Her family life resumes until Fred calls her from prison; she agrees to help him find a solicitor, to the dismay of Josh and Mike.
The journalist finds a location matching Fred's description of the barn, but Janet expresses doubt that the truth will ever be known and returns to family life.
The production was headed by ITV executive producer Jeff Pope, who considered it as the concluding feature in a trilogy of films about the most notorious British murder cases of the past century, the previous films being This Is Personal: The Hunt for the Yorkshire Ripper and See No Evil: The Moors Murders, which won multiple awards.
Co-producer Kwadjo Dajan researched and developed the project over four years after establishing contact with Janet Leach and consulting with Gloucestershire Constabulary.
[3] Janet Leach found it difficult to approach Dominic West in character on set because he was so convincing that it took her back seventeen years to her work with the murderer.
A later article by Phil Hogan in The Observer and The Guardian described Dominic West's performance as "worryingly close" but said "even with a set of chipped teeth, bad jumper choices and a rattling West Country burr, handsome Dominic could not quite conjure the Fred familiar from his demonic police mug shot.
What he did conjure, in one impressively seamless personality, were the strange warring traits of a man cheerfully sane and yet not quite there – helpful but manipulative, confiding but controlling, troubled but carefree, a composite that perfectly explained why the police wanted the presence of an 'appropriate adult'".
[6] Following its broadcast, the programme was also criticised by retired Gloucestershire Detective Superintendent John Bennett who said, "the series went far beyond any justifiable claims of 'dramatic licence' and 'simplification' by creating dialogue and scenes which did not take place at all, these just sensationalising the story and not furthering it, wrongly depicting how Janet Leach was treated and her involvement, giving her a kudos she far from deserves".
[6] "This series painting her as a 'victim' and wrongly portraying the sequence of events and her contact with and payment by the Mirror Group whilst grossly exaggerating her involvement is an insult to the true victims, their families, which very much includes the extended family of the Wests, the witnesses who so courageously gave evidence, the investigating team, and its professionalism, also the many professionals and others who worked so hard to unravel the horrific crimes and bring the Wests and others to justice".
We have not attempted to whitewash Janet – her portrayal in the drama is subtle and balanced, and shows an ordinary woman subjected to an extraordinary situation.
We depict her decision to accept the newspaper deal to sell her story, and how that was exposed in court during the trial of Rosemary West, as well as showing that her motivation was not simply financial.
We met former Detective Superintendent John Bennett on several occasions to discuss the making of a factual drama based around the case of Fred and Rosemary West.