The high court in Shah Alam, the capital of the Malaysian state of Selangor, sentenced former lawyer N. Pathmanabhan, 43, and farm hands T Thilayalagan, 21, R Matan, 22, and R Kathavarayan, 33, for the murders of cosmetics millionaire Sosilawati Lawiya, 47, her driver Kamaruddin Shamsuddin, 44, bank officer Noorhisham Mohamad, 38, and lawyer Ahmad Kamal Abdul Karim, 32, in Tanjung Sepat town Aug 30, 2010.
"The prosecution has proven its case beyond a reasonable doubt," the Malaysian Star quoted sentencing judge Akhtar Tahir as saying.
"I find all four accused guilty as charged."
The businesswoman and her three aides had gone to Tanjung Sepat in Banting district for a land deal but were later reported missing.
Pathmanabhan is said to be the mastermind behind the murders and money the motive.
Though the bodies were not recovered, all four were reportedly beaten to death, their bodies doused with petrol and burnt and the ashes thrown into a river.
Lawiya's was a rags-to-riches story. Daughter of a labourer, she used her savings of 13 years to start a cosmetics business that was worth millions of Malaysian ringgits.