A "secret" US cable of Feb 26 this year, put out by the whistleblower website and reported by Guardian, said that in a Feb 23 meeting in 2010, FBI Director Robert Mueller and Chidambaram discussed the case of Headley, who is in US custody.
The cable said: "Chidambaram insisted that the GOI (Government of India) have access to Headley: 'we must be able to say we had access, even if Headley did not speak'. He also requested access to Headley's spouse, Shaiza, who he said is in Chicago so GOI investigators can question her on the meaning of her alleged message to Headley that she `saw your graduation'."
It said that Chidambaram asked Mueller "whether GOI personnel could monitor and pass questions `in real time' to USG (United States Government) personnel conducting Headley's interrogation. Mueller replied that he would look into this possibility".
The Indian home minister asked for increased cooperation in cyber security, forensic cooperation and some financial initiatives and cooperation.
During the meeting, Chidambaram confided that "I have a feeling in my bones that Headley was not acting alone" in India and expressed frustration over what he characterised as Headley's false claim that he had no accomplices in India, the daily reported.
Chidambaram noted that the Indian government "would not file formal charges against Headley until the trial of Mumbai defendant Mir Kasab is finished for fear that Kasab would use the Headley charges as a way to delay conclusion of his own trial".
He complained that Pakistan had "done damn near nothing" to prosecute Mumbai-related terror suspects.
Ten terrorists from Pakistan sneaked into Mumbai and went on a killing spree over three days in November 2008, leaving 166 people dead.