A jury is continuing to consider its verdicts in the sex abuse case against the brother of Eurovision Song Contest winner and former Irish presidential candidate Dana Rosemary Scallon.
John Brown, 60, is accused of five counts of indecent assault against two girls under the ages of 13 and 16 at different times and locations in Northern Ireland and England during the 1970s.
Brown, of Bracknell, Berkshire, denies the alleged abuse or that his 62-year-old sister helped him to cover up the allegations.
Prosecutor Claire Howell told the jury at Harrow Crown Court, north west London, that the pair had both lied during Brown's three-week trial.
In her closing speech, Ms Howell said that Brown believes he is a victim of "an evil conspiracy to accuse him of abuse that he did not commit".
She argued: "The prosecution say that the people who have agreed to lie to you in this case are the defence witnesses.
"It's no sophisticated conspiracy - it's a cover-up from many years ago, at a time when you might think that cover-ups of this sort did happen for various reasons.
"And, having covered it up, it's very difficult for them to come clean about it for various reasons."
Ms Howell said Brown and his sister had given a "slick presentation" to the court, with exact dates and details.
Ms Scallon first achieved fame after winning the Eurovision Song Contest in 1970 with All Kinds Of Everything.
Born in London to a Northern Irish family, she went into politics in 1997, served as an MEP for Connacht-Ulster and twice stood as an independent candidate at presidential elections in the Republic.
She is currently facing defamation proceedings there brought by one of the complainants against her brother over a 2011 television interview.
Martyn Bowyer, for the defence, described the prosecution's case against her brother as "fuzzy" on the details. Brown is an innocent man who had been "consistent throughout", he said.
He asked the jury not to be influenced by recent high-profile child abuse scandals.
Mr Bowyer said: "I beg of you, do not let other cases or other personalities in any way colour your judgment and your verdicts in this case."
The jury were sent home for the day and will resume their deliberations tomorrow at 10am.