Mercury continues to rise in Chuadanga, crossing 41 degrees Celsius for the first time this season in early summer
Mostak Ahmed, 31, and Ismail Ali, 31, of Kewrha village, have also been fined Tk 50,000 each.
They will have to spend another six months in jail if they fail to pay the fine.
Additional District and Sessions Judge Waliul Islam acquitted two others as charges against them could not be established.
According to case details, the convicts used to harass the victim regularly on her way to school. Ahmed was scolded by locals during an arbitration over the matter.
Ahmed and his associates then abducted Begum from her home on June 21, 2007 and killed her by slitting her throat.
Her father filed a murder case over the incident accusing Ahmed and Ali the following day.
Police pressed charges against four men in court on Feb 28, 2008.