According to prosecution, Tamilarasan, Ramachandran and Kannan kidnapped Muthamilselvan on February 10, 2010 and later demanded Rs 10 lakh from his father for releasing his son.
The youth was secured after police arrested the three following a complaint from his father.
During the trial, Kannan died in road accident.
Salem Additional Sessions Judge Nasima Bhanu sentenced the two for life imprisonment besides slapping a fine of Rs 2000 each.