Fast track court IV judge Jitendra Kumar Mishra also imposed a fine of Rs 10,000 each on the convicts.
The four had killed Akhilesh Kumar, a driver, in a bid to loot his belongings on April 1, 2009 and later buried his body in a field in Jharkhand's Giridih district.
A murder case was registered at Laheri police station by the kin of the victim.
The police had cracked the case on the basis of call details of the victim's mobile phone and arrested the four.
