The first pair of terrorists, it is now believed, remained undetected on the base for nearly an entire day.
The six terrorists who entered the Pathankot
air force base to launch a deadly attack over the weekend were working to a clear plan. Divided into two teams, the first group (a pair of men) was meant to destroy India's fighter jets and attack helicopters, along with a fueling station and a building where ammunition was stored. To facilitate this, the other group of the four remaining Pakistani terrorists was tasked to firing indiscriminately and creating a diversion, allowing their companions to cause as much destruction as possible.
The first pair of terrorists, it is now believed by investigators, managed to enter the base
, located just 30 kms from the border with Pakistan, by noon on January 1. They remained undetected on the base for nearly an entire day.
Seven military personnel were martyred in the assault by the Pakistanis; another 20 were injured.
Investigators say the possibility of "insider or local help" for the terrorists is one of key points of investigation.
Officers from the National Investigation Agency or NIA are set to question
a staffer arrested from the base in 2014 on charges of spying for Pakistan's ISI. They will also interrogate Ranjith KK, who was posted at the air force base in Bhatinda in Punjab and was arrested just weeks ago on charges of espionage for the ISI.
The attack, investigators say, was also intrinsically linked to and facilitated by the flourishing cross-border drug trade in this part of Punjab.
A little past midnight on December 31, Salwinder Singh, a local police officer, had warned his seniors
that he had been abducted by four-five terrorists, who had snatched his phones and official car. Mr Singh's mobile was later used by the terrorists to call their handlers in Pakistan
- these calls were intercepted by intelligence agencies. Based on those and other inputs that included Mr Singh's alert about his car-jacking, an alert was sounded for military assets in the area by 3.30 pm on January 1.
When Group 2 of the four terrorists entered the base by scaling the 10-foot high, barbed-wire topped wall of a section of the base - the rope they used has been found - the first pair is believed to have been already present on the base for 24 hours.
Investigators believe that after crossing the border into India, they used a taxi whose driver, Ikagar Singh, was found with his throat slit on the road near his village. The taxi was found abandoned about 40 kilometres from the air base. But how the first pair of terrorists entered the base with their weapons -which included several machine guns - is still not clear.
The second group appear to have approached the Pathankot base in Mr Singh's SUV, though interrogators say his own account of what happened is riddled with inconsistencies.