"This will never bring our father back, but justice has been done."

Those were the words of Amjad Raja on Monday after millionaire tycoon Nicholas Van Hoogstraten was found guilty of sending career criminals David Croke and Robert Knapp to harm and intimidate his father Mohammed.

Croke and Knapp ended up stabbing Mr Raja five times before shooting him dead at point blank range in his Sutton home. Both were convicted of murder on Friday.

Mr Raja's family had waited more than three years, sat through court for three months and endured a nightmarish week-and-a half of jury deliberations, before seeing the Mulgrave Road grandfather's killers put behind bars.

After the jury found Hoogstraten guilty of manslaughter on an 11 to one majority, the Rajas hugged each other and joyfully took to their mobile phones to tell friends and relatives the good news. But amid the emotion of Monday's victory at the Old Bailey, Amjad admitted his father's battle with Hoogstraten was only half won, referring to the fraud writ lodged by Mr Raja against the notorious Brighton landlord just months before his murder.

By standing up to Hoogstraten, Mr Raja, 63, had put himself in the ruthless and violent magnate's firing line, as the events of the morning of July 2, 1999, so tragically proved.

Amjad, 41, said: "Seeking the truth, he sacrificed his life taking action against Hoogstraten. We intend to carry on with that legal action and hopefully get a positive result."

Of the tycoon, worth a reported £60 million, he said: "He's destroyed our family. He's taken from us a wonderful father who would have done anything for his children and his grandchildren."

He thanked those witnesses who had given evidence for the prosecution, saying: "I know how intimidating Mr Hoogstraten is."

Hoogstraten, 57, will be sentenced on October 2, pending a court and an independent psychiatric report, and trial judge Mr Justice Newman admitted he was considering jailing him for life. He was impassive as he listened to the verdict and quietly left the court after shaking hands with his barristers.

Knapp, 53, and Croke, 60 vicious men with a history of violence, intimidation and armed robbery may never leave prison. Mr Justice Newman said of them: "Those who conduct themselves in this way do not just turn their backs on civilised society, they deliberately withdraw from it.

"They confront society with a problem which this trial has proved society is well capable of meeting."