It’s almost a year since 16-year-old Brianna Ghey was stabbed to death in a park in Warrington.

She’d been lured there by two 15-year-olds - Scarlett Jenkinson and Eddie Ratcliffe - who carried out the most brutal and bloody attack.

They’ve now been jailed for life. But how did two seemingly innocent teenagers become utterly callous killers?

From ITV Granada, Rob Smith tells Gamal Fahnbulleh What You Need to know…