Several investigations teams are working to nab the killers of NIA officer Tanzil Ahmed who was shot dead on Sunday. Meanwhile, the state police Director General Office told AIR that Additional Director General (ADG) law and order Daljit Chowdahry is visiting the incident site in Bijnore district today. Yesterday, the state Chief Minister Akhilesh Yadav had also ordered state DG-Police to provide all necessary assistance to investigation agencies so that assailants could be arrested soon. Police sources told AIR that marriage video is being thoroughly examined to trace the culprits.<br/><br/>Earlier, a family member claimed that they had seen two unknown person at the wedding ceremony in which Tanzil Ahemd was present with his family at Sahaspur village in Bijonr district on the same day.