Assume Nothing

A woman says she's visited by men who she says tell her there is no point in pursuing Jonathan Creswell after she reported him for stealing her horse. Another is told police couldn't arrest him when she'd reported him for indecent exposure at the yard where they worked. And for the first time, journalist Tanya Fowles reveals details of a call she received trying to put her off the story.

Detective Sergeant James Brannigan has one last chance to convince his bosses to launch an investigation into Katie's death. Working on his own, he compiles a 20-page report of all the evidence so far. He says there are questions that need answers. He hopes senior officers will now decide the death needs to be looked at by a Major Investigations Team. But it is only when a young officer speaks up that the decision to have another look is made.

Detective Sergeant James Brannigan is able to speak to this series for the first time. He reveals how a call from journalist Tanya Fowles leads him to review the evidence gathered so far by his police colleagues into the murder. The more he uncovers, the more he believes an investigation is needed. He's just got to convince his senior officers.

Jonathan Creswell very nearly gets away with murder. He tells police Katie Simpson had tried to take her own life. He's the hero who'd tried to save her. But he is lying. He's eventually charged with her rape and murder. Now new witnesses say they'd tried to warn police of her killer's behaviours.

As Cameron Finnigan is sentenced at the Old Bailey his mum speaks out. She offers a rare, painful and deeply revealing insight into families caught in the fallout of 764.The BBC investigation explores what it will take to stop this network and the National Crime Agency reveal what they’re doing to combat the growing threat of online groups like 764.Written and Produced by Jo Palmer.For information and support on issues discussed in this series, visit bbc.co.uk/actionline.