Former EastEnders actress Gemma McCluskie was beaten to death by her brother after a row over an overflowing sink, a court has heard.
Cannabis-smoking Tony McCluskie had left taps on at the London flat they shared and Miss McCluskie, 29, thought this was the "last straw".
She drove home to ask him to leave but was never seen alive again, the Old Bailey was told.
Jurors were told McCluskie killed his sister, cut up her body and dumped her remains in a canal - before leading police on a "wild goose chase" after reporting her missing last March.
McCluskie, 35, of Pelter Street, Shoreditch, east London, has pleaded guilty to manslaughter but denies murder.
He says that he "blanked out" after arguing with her and has no recollection of killing her, the court heard.
Miss McCluskie played Kerry Skinner, the niece of Ethel Skinner, in the BBC soap in 2001.
Crispin Aylett, QC, prosecuting, said: "For some time, there had been tension between Miss McCluskie and her brother.
"To Gemma, this was largely as a result of the defendant's habitual use of cannabis - and its most toxic form, skunk.
"Gemma told a friend 'He's permanently stoned. He puts a spliff in his mouth first thing in the morning and doesn't know what he's doing'."
He said Miss McCluskie had discovered her brother had left taps on in the sink on Thursday, March 1 of last year and was "exasperated". Her friends later heard her arguing on the phone with her brother.
Mr Aylett said: "It is clear that Gemma regarded this incident as the last straw and that she wanted the defendant to move out."
The next day, McCluskie sent his sister a text pretending she was still alive and ending "Love ya xx", the court heard.
Her friends became concerned when they were unable to reach her and called or sent texts to the defendant, asking if he had heard from her.
He reported her missing to police, who classed her disappearance as low-risk based on details given by her brother.
The following Sunday, McCluskie told officers that a former boyfriend owed her money.
One hundred of her friends held a meeting in a local pub and then distributed leaflets appealing for help.
Her brother did not turn up at the pub until after the meeting had broken up, said Mr Aylett.
On the following Tuesday, a woman on a barge on the canal in Hackney, east London, noticed a floating suitcase. It hit the vessel and sprung open.
Mr Aylett said: "Inside was a female torso, no legs, no arms and no head." Miss McCluskie had been identified by a small tattoo on her body.
Over the next fortnight, her arms and legs were recovered separately from the water.
But her head, which had been dumped in the canal at the same time, was not found until September.
Mr Aylett said McCluskie told police that his sister had been seen in a kebab shop after she went missing, and that she had visited their mother in hospital.
But scientists had found blood in the bathroom and a blood-stained knife in the kitchen of the flat.
Police discovered that a man with a suitcase, who matched McCluskie's description, had taken a minicab to the canal the day after his sister disappeared.
Blood was found in the boot of the car, Mr Aylett said, and McCluskie's father and brother "no doubt with heavy hearts" said they recognised him from CCTV.
Mr Aylett continued: "The defendant must have killed Gemma, no doubt in the course of a quarrel."
Bruises were found on Miss McCluskie's arms and legs made before she died, and there were signs she had been struck over the head at least twice with a blunt instrument.
Mr Aylett said the prosecution did not accept the defendant's claims that he did not know how he killed his sister, nor remember cutting up and dumping her body.
"No doubt he did it in the heat of the moment, no doubt he soon came to regret what he had done," added Mr Aylett.
"He did everything he could to put himself beyond suspicion."
The trial continues.