Suspecting is one thing, having proof is another. They knew that they did not have any actionable or prosecutable evidence against him. And since he was working in the high commission, they wouldn't arrest him unless they had clinching evidence.it becomes a crime if he is suspected of being an agent- indian agent- that changes every thing-
wondering how much fake is in his stories of bravado-
I don't know if you know this, but embassy staff are the most obvious cover that every country gives to their spies. That's what India, Pak and everybody else does. And counter intelligence units therefore constantly monitor or at least keep tabs on embassy staff, especially the non essential ones. That is probably why Doval was being tailed.
Since he was a big shot in the Indian intel community, my guess is that he was not there to do field work - he was there as a coordinator and analyst, not as an agent. So he wouldn't have gone around snooping, he would simply stay in his office and analyse the intel reports given to him by the invisible and covert spies. Usually it's senior people who do the analysis.
Do you think Pakistan could possibly be unaware of the real nature of his job, and do you think he was unaware that they were aware? Pak would do a background check of everybody working in the high commission - and this fellow was a senior officer in the IPS. It doesn't require a James Bond or Sherlock Holmes to figure out why he was working there. But since he wouldn't be involved in intelligence collection, they would never be able to arrest him. Hence the best they can do is to accost him when they can, and spook him informally.
I'm sure there are Pakistani intel analysts working in a similar manner in India as well. Unlike the grunts on the ground, these people are safe from capture.