District Additional and Sessions court judge M G Padmini also slapped a fine of Rs 5.5 lakh on K K Mammad yesterday out of which Rs three lakh is to be paid to the widow of the victim and Rs one lakh to his mother.
The educational and other expenses of the victim's children would be borne by the Forest Department till they attain 18 years, the judge said.
The Guard Devadoss and Forest Officer M K Rajeev raided the forest area on a tip off that a man had entered with a gun for hunting on March 25, 2010. On seeing them, Mammad opened fire at them and Devadoss sustained serious injuries.
Mammad also opened fire at Rajeev, who escaped unhurt, and fled away. Later he was arrested near Thamarassery.