Becky Watts was murdered as part of a plan to kidnap the teen - which had a "sexual motive behind the scheme", a court has heard.
16-year-old Becky was strangled in her bedroom at her home in Crown Hill, Bristol before, the prosecution allege, her step-brother Nathan Matthews and his girlfriend, Shauna Hoare, removed her body to their house, dismembered it using a knife and power-saw and "carefully packaged" her body parts into bags and boxes.
There followed a deliberate, carefully planned, and grotesquely executed plan to cover up her killing.
Others, including James Ireland, and Donovan Demetrius, helped to remove the boxes and bags.
The prosecution say her death was part of a plan to kidnap Becky, where items were taken to her home to carry it out.
There is a good reason to believed that there was also a sexual motive behind the scheme, arising from a shared unnatural interest in attractive teenage females.
A teenager was killed by her step-brother in a "violent struggle" before her body was cut up with a power saw and a knife, a court heard.
Becky Watts allegedly told a friend that Nathan Matthews, who is on trial for her murder, described how he would kill her in 2013.
Nathan Matthews, the step-brother of Becky Watts, has admitted to killing the teen - but denies he murder her.