Tunda was produced in Rohtak and Sonepat courts on Saturday in separate cases related to terror attacks.
A bomb was planted in a private bus at Panipat bus stand on February 1, 1997, killing a 10-year-old boy and leaving around dozen others injured.
Pakistani national Mohammad Hussain alias Zulfikar was found guilty in the case and was awarded life sentence by a Chandigarh court in 2008.
Deputy superintendent of police, Sonepat, Balbir Singh told HT over phone on Sunday that Tunda's involvement was suspected in the bomb blast cases in Panipat, Rohtak and Sonepat.
“As there was no material evidence against Tunda for his direct role in Panipat blast case, we did not require his custody for any questioning. Tunda had trained terrorists in making bombs and he is named as the main conspirator in the three blasts that rocked Haryana,” said Singh, who is the head of special investigating team (SIT) probing three terrorism-related cases.