Nicholas van Hoogstraten is reputed to have a £500 million fortune, ranking him alongside the Rothschilds.
His £40 million neo-classical copper-domed mansion at Framfield, near Uckfield, is said to be the most expensive private house built in Britain for a century.
His fortune was based on property deals. He is said to have terrorised tenants, describing them as "filth". A judge once described him as the "emissary of Beelzebub".
Another of his former business associates, Michaal Hamdan, fled to the Lebanon, allegedly fearing for his life, shortly before he was due to give evidence.
Hamdan had implicated Hoogstraten in the killing of Mr Raja, the court was told during legal arguments, held in the absence of the jury.
He alleged Hoogstraten had said he wanted to get rid of two people - one of them Raja.
After Hamdan flew to Beirut, the judge ruled that his statements could not be read to the jury in his absence so they knew nothing of his allegations.
Hamdan heard Hoogstraten had said he would not make it to the trial and if Hoogstraten went to prison, neither Hamdan nor his family would survive.
"He feared he was going to be murdered," said Detective Inspector Andrew Sladen during the legal arguments.
Hoogstraten emphatically denied he was responsible for Hamdan's fear, saying it was nonsense and a figment of the police's imagination.
Hoogstraten's girlfriend Tanika Sali also changed her mind about testifying as a prosecution witness.
Mr Justice Newman referred Miss Sali's actions to the Attorney General after she retracted her police statements and refused to go into the witness box.
She turned up at court wearing an expensive new outfit, which she said had been bought with a whip-round from friends.
Hoogstraten denied having anything to do with Mr Raja's murder, ridiculing the prosecution's allegation that he had paid Knapp around £7,000 by instalment.
His defence lawyer, Richard Ferguson QC, said: "Mr Hoogstraten is a man of means. Do you not think that if he had wanted Mohammed Raja killed, he would have had a vastly more sophisticated plan?"
Hoogstraten had allegedly told Mr Raja's son Amjad: "Your dad is a maggot. He does not know what I am. We pick thorns who are a pain and we break them."
The man known as Britain's most hated property tycoon accepted he had a volcanic temper and had in the past threatened to kill people.
But he told the court it was simply anger, adding: "There have been no dead bodies."
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