Additional District and Sessions Judge Mafroja Parvin pronounced the verdict on Wednesday afternoon.
The convicts are Helal Uddin Turki, 18, Roni, 19, Saddam, 18, Niaz, 15, and Aktar Mia, 20.
The court also acquitted eight others as they were found not guilty.
According to the case statement, miscreants stabbed Towkir to death centring a trifling matter on September 24, 2009.
Towkir’s father Abdul Barik filed a case with sadar police station against 12 people on the following day.
Police had submitted charge sheet against 13 people.
Expressing discontent over the verdict, plaintiff Abdul Barik said they would appeal in the High Court.
On the other hand, convicts’ lawyer Advocate Abul Khayer expressed his satisfaction over the verdict.