A duo was awarded life term on five counts for killing a woman, her daughter and granddaughter.
The sentences are to run consecutively.
District and sessions judge Sarojini Devi found the accused Kamaraj and Ilango guilty of murdering Kalyani (50), her daughter Kalaiarasi (23) and granddaughter Karanya (6) at their house at Vennamalai near here in December 2011.
They took away 60 sovereigns of gold jewellery and some cash.
On January 18, 2012, the Vengamedu police arrested Kamaraj, Ilango and Santhanam in connection with the murders.
Santhanam died last year during imprisonment in Salem jail under mysterious circumstances.
The judge slapped life term for each count of the three murders, criminal trespass with an intention to murder and for robbery with murderous intent.
Fifty-one witnesses testified on the prosecution side, while defence lined up four witnesses.
