Punjab police officer Salvinder Singh had a a lie-detector test.
After conducting a lie-detector test on senior Punjab police officer Salvinder Singh, the NIA will now subject two others, including his jeweller friend, who were kidnapped with him by suspected JeM terrorists before they attacked the Pathankot air force station, to the test.
Besides, the caretaker of a shrine the officer was claimed to have visited before the incident will also be subjected to polygraph test.
NIA sources said after the name of Mr Singh was cleared, scientific tests on his jeweller friend Rajesh Verma, cook Madan Gopal and caretaker of 'Panj Peer Dargah' Somraj would be conducted this week.
Mr Singh, who was questioned about the sequence of events ahead of the terror strike for close to a fortnight and subjected to various tests, may be called again if something new emerged from the polygraph examination of the other three.
While Mr Verma was left on the road with a slit throat on the intervening night of December 31 and January 1, Gopal and Mr Singh, currently posted as Assistant Commandant of 75th battalion of Punjab Armed Police, were released some distance away before the terrorists left to attack the air base.
Meanwhile, the NIA probing the audacious attack said the terrorists, at least some of them, had taken shelter in a shed inside the air base on the morning of January 1 itself. The anti-terror agency is probing whether somebody at the strategically important facility had facilitated their entry there.
The first call by the perpetrators of the attack was intercepted at around 9 AM on January 1 during which one of the terrorists is said to have told his handlers somewhere near Rawalakote in Pakistan that they had entered the "camp", triggering alarm bells in the security establishment. Immediately, security was tightened at all the "camps" including the IAF base and army and Punjab police establishments.
Terrorists involved in July 27 Dinanagar police station attack in neighbouring Gurdaspur district had also wanted to move towards an army installation in Pathankot, as per the pre-entered GPS position recovered from them, sources said.
The focus of investigation has now shifted to whether the terrorists were provided help internally at the base as they apparently knew which of the sheds belonging to Military Engineering Services was vacant, they said.
The terrorists could also manoeuvre from one side of the base to another with ease, suggesting they either knew the topography of the IAF base or were guided.
The terrorists had also been receiving calls on the phone of Singh's jeweller friend recovered from the site of encounter, sources said.
The terrorists were engaged in an 80-hour gunbattle with the security forces at the IAF base from the intervening night of January 1 and 2. Seven security personnel were killed, while four bodies of terrorists suspectedly belonging to Jaish-e-Mohammed were recovered.
Two others are believed to have been burnt in the building where they had holed up during the encounter.