Nathan Matthews could die behind bars after being sentenced to life imprisonment and told he will serve at least 33 years for the murder of his stepsister Becky Watts.
Girlfriend Shauna Hoare, 21, will serve 17 years' imprisonment for the manslaughter of the 16-year-old.
Trial judge Mr Justice Dingemans was in tears as he started paying tribute to Becky's family at the end of his sentencing remarks.
Matthews, 28, and his girlfriend targeted the 5ft 1in teenager due to their shared dislike of her and their interest in petite teenage girls.
They devised a plan to kidnap Becky from her home in Crown Hill, Bristol, and drove there on February 19 while she was alone.
Detectives say the truth about what happened to Becky that morning may never be known but a pathologist found she died of strangulation.
Becky suffered more than 40 injuries to her body as she bravely fought for her life against porn-obsessed Matthews and his cold-blooded partner.
After her death, the pair dismembered Becky with an £80 circular saw in the bathroom of their squalid home in Cotton Mill Lane - less than two miles away.
They callously laughed as they watched a parody of a Disney Frozen song, entitled Do You Want To Hide A Body, while Becky's remains lay just rooms away.
A jury at Bristol Crown Court took just three hours and 27 minutes to convict Matthews of Becky's murder, while Hoare was found guilty of the teenager's manslaughter.
Both were convicted of kidnap, perverting the course of justice, preventing a lawful burial and possessing two stun gun torches.