Video report by ITV News reporter Sejal Karia
'Fake Sheikh' Mazher Mahmood is facing a string of multi-million pound lawsuits after being convicted of tampering with evidence in the collapsed Tulisa Contostavlos drugs trial.
The 53-year-old "King of the Sting" and his driver Alan Smith, 67, were found guilty of plotting to pervert the course of justice at the Old Bailey.
Following the verdict, it was announced 18 civil claims were now being launched against Mahmood which could total some £800 million.
Media lawyer Mark Lewis said the claims would "dwarf" those brought following the phone- hacking scandal.
The trial had heard that Mahmood and Smith conspired to hide evidence in the N-Dubz star's trial, which was thrown out at Southwark Crown Court in July 2014.
The singer had been accused of arranging for Mahmood to be sold £800 of cocaine by one of her contacts following an elaborate sting for the Sun on Sunday in May 2013.
During a meeting at the Metropolitan Hotel in London, Mahmood posed as a film producer and plied Miss Contostavlos with alcohol as they discussed an acting role alongside Hollywood star Leonardo DiCaprio.
As Smith drove the former X Factor judge home to Hertfordshire, she allegedly spoke about a family member who had a drugs problem.
When he was interviewed by police about the journey more than a year later, Smith, of Dereham, Norfolk, recalled the conversation.
But a day later, after speaking to Mahmood and emailing his draft statement, the singer's anti-drugs comments were removed, the court heard.
At a pre-trial hearing, Mahmood denied being an "agent provocateur" or that he discussed the drugs conversation with Smith.
But when questioned at length in the trial, Mahmood appeared to concede he had talked to Smith about what Miss Contostavlos had said about drugs in the car.
For more than 25 years, Mahmood has enjoyed a position as "King of the Sting" at the now defunct News of the World, Sunday Times and Sun on Sunday, with Smith as his "right-hand man".
The journalist, from Purley, south London, has been suspended by News UK since the collapse of the Tulisa trial.
The Criminal Cases Review Commission is currently reviewing six cases involving celebrities who were convicted following involvement with Mahmood.
He claims to have helped put more than 100 criminals behind bars and risked his life on a daily basis to lift the lid on the murky world of crime.
Paedophiles, arms dealers and drug dealers have all found themselves at the centre of his stories.
Celebrities and public figures, including the Countess of Wessex, who was taped calling the Queen ''the old dear'', and Sven-Goran Eriksson, who revealed his plans to quit as England head football coach were also included.
The prosecution asked for costs to be awarded totalling £37,929.
Judge Gerald Gordon adjourned sentencing until October 21 and allowed the defendants bail.
As he was leaving court, Mahmood declined to comment to journalists or say whether he would be launching an appeal.
Ben Rose, Tulisa Contostavlos's defence lawyer, said: "The real scandal in this case is that Mahmood was allowed to operate as a wholly unregulated police force, 'investigating' crimes without the safeguards which apply to the police.
"It was obvious from the outset that Tulisa should never have had to go to court.
"If Mahmood's evidence had been properly stress-tested instead of accepted wholesale by the CPS, we are confident it would have come to the same conclusion.
"Investigative journalists do important work, but Mahmood clearly went too far."