The National Investigation Agency (NIA) has taken into custody a Kashmir resident who investigators say played a key role in the Red Fort area car bomb blast, that killed 13 people on November 10.

The arrested man, Amir Rashid Ali, was picked up from Delhi. The car used in the explosion was registered in his name, the agency said in a statement.

According to investigators, Amir had “conspired with the ‘suicide bomber’, Umar” and helped set the ground for the attack.

The NIA’s release marks the first time the agency has publicly described Dr Umar Un Nabi, who was behind the wheel when the car exploded, as a “suicide bomber”.

It is also the first official reference to the blast vehicle as a “vehicle-borne Improvised Explosive Device (IED)”.

Amir, a resident of Samboora in Jammu and Kashmir’s Pampore, had allegedly travelled to Delhi to help purchase the car that later became the “vehicle-borne IED”, the NIA said.

Investigators have now forensically confirmed the identity of the deceased driver as Umar Un Nabi.

A resident of Pulwama and an assistant professor in the general medicine department at Al Falah University in Faridabad, Umar had vanished from regular life and resurfaced in the blast investigation only through forensic matches and digital traces.

Another vehicle belonging to Umar has also been seized. It is currently being examined for leads.

The NIA, which took over the investigation from Delhi Police, has been running an extensive search operation. So far, 73 witnesses, including several of the injured, have been examined.

Working with Delhi police, Jammu and Kashmir police, Haryana police, Uttar Pradesh police and central agencies, teams have been moving across states to stitch together the wider network that may have supported Umar or Amir.

The agency says it is following “multiple leads” to identify others who may have helped plan or execute the “bombing”.