Sohel Rana, Molin Ghorami, Masum Billah and Al Amin were given life imprisonment. The other two convicts are Hiru and Liton.
The court also fined them Tk 10,000 each.
According to the prosecution, the accused called Shakil Sikdar, 20, over phone from his house on March 9, 2014.
Later, they strangled him and dumped his body in a paddy field at Singkhali village as per their previous plan to snatch Shakil's motorcycle.
Then, the convicts took the motorcycle and kept it at Liton's house. Later, the motorcycle was hidden at the house of Liton's cousin Hiru.
Police recovered Shakil's body from the paddy field the following day.
Later, Shakil's mother Alo Begum filed a murder case at Bhandaria Police Station.
After examining all the records, Pirojpur District and Sessions Judge Md Mohiduzzaman handed down the verdict.
Also read: Three policemen get life term in first verdict over custodial death