Becky Watts was murdered and then her body was dismembered with a knife and a power saw by her stepbrother and his girlfriend, a court has heard.
The 16-year-old was killed in the bedroom of her home in Bristol by Nathan Matthews, 28, and Shauna Hoare, 21, after a failed attempt to kidnap her for a sexual motive, jurors were told.
Matthews denies murder and conspiracy to kidnap. Hoare denies murder, conspiracy to kidnap, perverting the course of justice, preventing a lawful burial and possessing a prohibited weapon, namely two stun guns.
It was also said the pair shared an "unnatural interest in attractive teenage females".
The day after the alleged murder, one of them typed "Do you want to hide a body?" into a YouTube search.
Opening the case, prosecutor William Mousley QC told the Jury: "She was suffocated, despite her fighting for her life. There followed a deliberate, carefully planned and grotesquely executed plan to cover up her killing."
Mr Mousley told the jury the day after Becky's death Matthews bought bottles of drain cleaner and a circular power saw, gloves, a face mask and goggles.
He also told jurors that two stun guns found at the home of Matthews and Hoare, which "may have been intended for use in the planned kidnap"
Another couple, who stored the dismembered body in their garden shed, have pleaded guilty to assisting an offender. Karl Demetrius, 29, and his girlfriend, Jaydene Parsons, 23, admitted the charge at an earlier hearing at Bristol Crown Court.
They told the court they "did not know or believe" the bags contained Becky's body, instead believing it held drugs or clothes.
Donovan Demetrius, 29 - Karl's twin brother - and James Ireland, 23, are also charged with assisting an offender, which they deny.
The case continues.
