The convicts are former sub-inspector Jahidur Rahman, former assistant sub-inspectors Qamruzzaman Mintu and Rashedul Islam of of Pallabi Police Station and their informers Md Sumon and Md Russell.
Metropolitan Sessions Judge's Court Judge KM Emrul Kayesh passed the order.
The court also fined each of the three cops Tk 1 lakh , in default, to suffer six-month more jail.
Each of them was also directed to pay Tk 2 lakh as compensation to the victim’s family otherwise ,they won’t be allowed to file appeal against the verdict with the High Court.
Police informants Sumon and Russell were also fined Tk 20,000 each, in default to suffer three-month more jail.
Among the accused, two ASIs and police informant Russell have been on the run.
Victim’s brother filed the case on August 7, 2014. The court framed charges against the five on April 17, 2016.
The case statement said Jonny attended a wedding ceremony in Pallabi's Irani camp at sector 11 on February 7, 2014 where he locked into an argument with police informant Sumon as he had been harassing some girls at the programme.
At one stage, Sumon left the party after being slapped by Jonny and threatened him of dire consequences.
After half an hour, police picked up Jonny and tortured him brutally at Pallabi police station.
Injured Jonny was taken to a hospital where he succumbed to his injuries.