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.

In a chilling look at how screens become crime scenes, we uncover a murder that was plotted in Romania and live streamed to 764 members worldwide.

The investigation explores the power of online manipulation and the worrying reach of 764.

Written and Produced by Jo Palmer.

For information and support on issues discussed in this series, visit bbc.co.uk/actionline.

Uncovering what happens inside 764’s chatrooms and its devastating toll on victims and families who are caught in the web of a network so dangerous, global law enforcement can barely keep up.

We meet a Canadian mother, whose daughter was drawn into the group’s grip, revealing how 764’s tactics push families to the brink and leave no one untouched.

Written and Produced by Jo Palmer.

For information and support on issues discussed in this series, visit bbc.co.uk/actionline.

Teenager Cameron Finnigan from Horsham in Sussex is arrested in a dawn raid. Behind it all is a shadowy online network called 764, so dangerous it’s being hunted by the FBI and global law enforcement.

The BBC investigates how Finnigan became entangled in a world where teenagers are coerced into live streaming rituals, self-harm and murder plots.

Presenter Jo looks deeper into the predators behind 764 and explores how they are reaching vulnerable children in their bedrooms.

Written and Produced by Jo Palmer.

For information and support on issues discussed in this series, visit bbc.co.uk/actionline.

They are a terrorist organisation who believe ‘no lives matter.’ They search for and extort children and young people, with deadly results. This is the story of the far right Satanist group called 764. Written and Produced by Jo Palmer. For information and support on issues discussed in this series, visit bbc.co.uk/actionline.

A fierce warrior turned master strategist, he led elite SAS troops on missions that shifted the tide of World War II. Decorated four times yet denied the Victoria Cross. Was it down to a typo or a face that didn’t fit? Today, his legend burns brighter than ever, fuelling a renewed campaign to honour him with the Victoria Cross.

Blair Mayne instils a maverick form of discipline, mourns a brother-in-arms, and forms the tip of the spear to liberate Europe from the Nazis.