The sister of the murderer who killed the City banker John Monckton has been jailed for four years for giving him a false alibi.
Laura Campbell even made reminder notes of her lies to protect her half-brother Damien Hanson after he knifed the wealthy financier to death in front of his wife and daughter.
Hanson, 25 - nicknamed "the Devil's Child" - was on parole for an earlier attempted murder when he killed Mr Monckton during a robbery at the family's Chelsea home.
But Campbell, 20, told police her brother had been watching EastEnders with her at a friend's flat on the night of the murder.
Her lie was exposed when the friend, Sade Haye, refused to play along.
Even after Hanson got three life sentences for the murder, Campbell kept lying. Only last week, seven days before she was due to stand trial, she finally admitted her guilt.
Her admission saved Ms Haye, the Crown's star witness, from having to testify while her three-month-old baby was in intensive care.
Campbell earlier pleaded guilty to two counts of perverting the course of justice and one of perjury.
On the evening of 29 November 2004, Hanson and his drug-dealing accomplice Elliot White posed as postmen to trick their way into the Moncktons' multi-million pound home.
Inside Hanson stabbed Mr Monckton's wife Homeyra twice in the back, nearly killing her. She was saved only by a 999 call by their nine-year-old daughter Isabelle, who witnessed the attack from the top floor of the terraced house at 30 Upper Cheyne Row.
Hanson took £4,000 of jewellery from Mrs Monckton - including a pair of costume jewelry earrings - before he turned to her husband.
White held the 49-year-old banker Legal and General director in a bear hug while Hanson knifed him repeatedly.
Hanson will serve a minimum of 36 years for murder, attempted murder and robbery. White was sentenced to 18 years for charges including manslaughter.
Yet Campbell's version of the night's events, which she had penned down in her black diary, looked quite different.
"Monday left about 4 o'clock," she wrote. "Sade met me at the bus stop outside the pizza shop. We caught bus to her house. Damien phoned to say he was coming.
"I plaited Sade's hair. I corn-rowed the top of her hair in the living room. Nobody was in," her entry went on.
"We watched EastEnders. He (Hanson) left about 10 o'clock. He went to Brixton and I went home."
The notes "had the appearance of prompt cards, which would remind her of the story she would have to tell", said prosecutor Parmjit Cheema.
"This shows the level of planning and sophistication this plan had and the preparation for giving evidence in court."
Campbell had been on bail since her arrest early last year. But Judge Charles Byers withdrew bail and said her "serious offences" demanded a prison term of "some length".