The widow of the Earl of Shaftesbury and her brother have each been jailed for 25 years after being found guilty of his murder by a French court.
The 10th Earl of Shaftesbury's body was found in April 2005
Anthony Ashley-Cooper's third wife, former nightclub hostess Jamila M'Barek, 45, had denied paying her brother Mohammed to murder her husband.
They had claimed the 10th Earl of Shaftesbury, who had homes in Hove and London, died during a drunken row.
His badly-decomposed body was found in a remote ravine in the Alps in 2005.
The prosecution said Ms M'Barek paid her brother 150,000 euros (£105,000) to kill the earl, because he was in the process of divorcing her and denying her the chance to inherit valuable properties in France and Ireland.
The 66-year-old playboy aristocrat went missing from his hotel on the French Riviera on 5 November 2004.
The body was found five months later.
Mr M'Barek, 43, admitted killing him, but said he strangled him "accidentally".
"I did everything I could to try and save him - I gave him mouth-to-mouth," he told the court in Nice.
Ms M'Barek denied she had married the Earl for money, saying she had always been prosperous and marrying him was a "curse".
Mohammed and Jamila M'Barek said the earl died in a drunken row
Nicholas Ashley-Cooper, the late peer's second son and now the 12th Earl of Shaftesbury, said he did not believe Ms M'Barek ever loved his father.
"I believe that she is manipulative and scheming, and ultimately an evil person," he said.
The 29-year-old sat in court throughout the four-day hearing with his mother Christina Cassell and aunt, Lady Frances Ashley-Cooper.
"During this trial we have heard the words of Mohammed and Jamila and we have seen the evidence brought before us," he said.
"It further confirms the type of people we thought they were - cold, deceitful, and without compassion for a man they murdered and betrayed.
"I don't understand how people can place no value on human life, and I truly pity them."
Speaking after verdict his said: "I believe justice was done and we are satisfied with the 25 year sentences given to both defendants.
"During the trial we heard a lot of excuses and I don't think we saw any remorse or compassion from the accused, but I was expecting that from the kind of people they are."
Franck de Vita, Ms M'Barek's lawyer, said it was a "bad day for justice", and added that his client would be launching an appeal.