Lucknow, Apr 5 (IANS): The director general of police has been "directly and personally" monitoring the brutal killing of NIA official Tanzil Ahmad in Uttar Pradesh.

According to an official, following the intervention of Chief Minister Akhilesh Yadav on Monday, Additional Director General of Police (Law and Order) Daljeet Chowdhary was going to Bijnor to visit the crime scene and review the progress made in the case.

The police, so far, had only been assisting the National Investigation Agency (NIA) and other central agencies in the probe, providing them logistical support.

The investigating team has zeroed in on a video clip of the wedding which Tanzil attended and on the way back home shot dead, sources said.

A man shown in the video was at the centre of the probe, as no one was able to identify him as belonging to either the bride's or groom's party.

NIA officials believe that the man shown in the clip could be the one who killed Tanzil.

"We are taking the matter ahead and hope to get some vital clues by Tuesday evening," an NIA official said.

He also said that a recce of the crime scene was done three days before the actual attempt.