Saini, as first reported in The Sunday Express on July 1, is alleged to have introduced US diplomat Rosanna Minchew to her Indian “contacts,” including NSC secretariat systems analyst S S Paul who is already in custody.

A former Navy commander, Saini headed the National Information Security Coordination Cell in the NSC that reported to National Security Adviser M K Narayanan. He also maintained close contact with Minchew and on March 31, quit to join Microsoft.

Asked what action Microsoft planned against Saini given he’s under probe, Rakesh Bakshi, Legal and Corporate Affairs Head of Microsoft India sent this statement to The Indian Express today: “Microsoft respects the law of the land in any of the countries it operates in and will cooperate with all concerned authorities on any issue of concern to them. More specific to this issue, it pertains to an individual in his previous employment and we believe it would be inappropriate for us to comment on it.’’

The crucial missing link, investigators said, is now Minchew who, it now transpires, was under active surveillance when the breach was detected but was able to leave the country. How Minchew could leave despite being under watch is a question still unanswered.

Sources said the issue will be raised through “institutional channels” between Indian and US intelligence agencies. US Ambassador David Mulford did hold meetings with top officials in the Ministry of External Affairs today but New Delhi is yet to take up the matter with Washington.