Becky Watts murder was culmination of 'sexually motivated' kidnap
Becky Watts' step-brother Nathan Matthews and his girlfriend Shauna Hoare have been found guilty of killing her following a sexually motivated kidnapping plot. But how were they brought to justice?
"Most people don't understand the concept of mine and Nathan's relationship. They never have understood it. Things that seem completely normal to us wouldn't seem normal to others."
This is how Shauna Hoare sums up her six-year relationship with Nathan Matthews.
There was little evidence to physically link the 21-year-old with Becky's death - her fingerprints were not found on incriminating items.
And while minuscule amounts of her DNA were discovered on two bags containing parts of Becky's body, and on a face mask thought to have been used after the attack, experts could not say with confidence whether she had ever actually touched them.
Matthews, on the other hand, admitted much of it - killing Becky and using a circular power saw to dismember her body in their bath, before hiding her remains in a nearby shed.
He said he had only intended to scare Becky by kidnapping her, explaining that he had become frustrated by the way he said his step-sister had been treating his disabled mother.
Matthews insisted he accidentally killed her and then went to extreme lengths to prevent the family finding out.
'Kidnap from school'
But, as the police continued to gather evidence as the months progressed, a different and even more disturbing picture began to emerge.
Text and Facebook messages between Matthews and Hoare suggested a shared sexual interest in teenage girls and evidence they had already considered kidnapping one.
In December 2014, little more than two months before Becky's death, Matthews sent a text to Hoare: "Bring me back two pretty schoolgirls then :)" to which she replied: "LOL yeah, I will just kidnap them from school."
Later that day she texted him to say she had seen a "very pretty girl... Almost knocked her out to bring home LOL".
When Matthews replied "DO IT", she wrote: "LMFAO yeah, I will just go back in time to when I saw her then time travel with her to the attic, LOL, XOXO".
Matthews did not hide his attraction to teenagers from his partner, who was only 15 when they met. He was 21 at the time.
He would point out "pretty" girls to her and say he would "give her a go".
Hoare said she would answer him sarcastically, as a way of showing her disapproval without overtly challenging him - and that explained the text messages.
But prosecutor William Mousley QC said those messages, together with pornographic websites bookmarked on the phone she shared with Matthews, gave "a pretty good indication as to what Shauna Hoare is really like".
Her "shared interests" with Matthews extended to three-way sex with pretty girls, he said, adding that the pair planned to kidnap Becky and take her back to their attic to be used as their "sexual plaything".
Among the pornography found on devices in the house was a video about the rape of a teenage girl.
Matthews insisted the kidnapping plan was his alone, and he dismembered Becky's body single-handedly with a power saw.
He claimed he did this without damaging the bath, and with his eyes shut.
Hoare said she knew nothing about any of this.
In the witness box, they cut very different figures.
While Matthews was hunched over and often in tears, Hoare was calmer and more confident.
The prosecution suggested she was a "very cold individual" who had first put the idea of kidnapping Becky, whom she did not like, into Matthews' head.
While she was initially only charged with attempting to pervert the course of justice, a combination of the messages between the pair and the "sheer implausibility" of her story formed the core of the prosecution's case.
Rachael Scott, head of the South West complex case work unit for the Crown Prosecution Service (CPS), told the BBC Hoare's original explanation just "didn't stack up" and she must have known what was going on.
The texts, once they came to light, "seemed an appropriate motive for what Shauna Hoare and Nathan Matthews did", said Ms Scott.
Injuries inflicted to Becky's body after her death and the "grotesque" way her corpse was treated betrayed the couple's "contempt" for the teenager, the prosecution said.
Det Supt Mike Courtiour told the BBC in 30 years as a police officer he had never been involved in a case like it and what Matthews had done would have "a lasting effect on everyone involved".
"From a personal point of view... this will leave a significant impression as one of the most horrendous cases that I have been involved in and dealt with."