The trial over the alleged torture and murder of a nanny by her employers is “stranger than fiction”, a jury heard.
Prosecutor Richard Howell QC told the Old Bailey Sabrina Kouider and Ouissem Medouni treated French national Sophie Lionnet as “less than human”.
The couple blame each other for killing Ms Lionnet, whose body was burnt in the garden of their Wimbledon flat.
The pair admit perverting the course of justice by disposing of the 21-year-old’s body but deny murder.
In his summing up speech, Mr Howell said the accused were driven by a “preposterous” obsession with Ms Kouider’s ex-boyfriend, and former Boyzone pop star, Mark Walton.
“Of all the cases this historic building has heard, this must without hesitation enter the category of the more bizarre,” Mr Howell said.
“Expressions such as ‘you really could not make it up’ and ‘truth is stranger than fiction’ come readily to mind.
“The defendants made a truly odd couple. There is a unique bond between them that has kept them together on and off for many years, a bond based partly in love and something close to it.
“But, as far as this trial is concerned, the point that really matters is that together they were a truly toxic combination.”
During the trial, Ms Kouider, 35, and Mr Medouni, 40, were accused of torturing Ms Lionnet in the lead-up to her death.
Mr Horwell said they regarded “submissive” Miss Lionnet as “expendable” and killed her out of “revenge and punishment”.
Mr Walton, a founder member of Boyzone, was praised by Mr Horwell for his “integrity and honesty” in giving evidence to the court.
He added: “Walton is a wealthy man – and good luck to him for that – but it is of course a truth universally acknowledged that a single man in possession of a good fortune will often be parted from it.”