The CBI had sounded out the government on its intention to proceed against former telecom minister A Raja earlier this year but was discouraged from going ahead.
Sources associated with vigilance administration said the CBI did not push the envelope at the stage, conscious of the embarrassment that would be caused to the government if a serving minister was raided by the anti-corruption bureau.
"They (CBI) had sounded out the government about findings implicating Raja some months ago … but they did not get a positive response," a key government functionary said.
It was in this context that a decision was taken to first get the telecom minister to step down before investigators would get a free hand. The Central Vigilance Commission - the first to raise questions about the 2G spectrum allocation - had already conveyed its assessment to the government, indicting the telecom minister for the twists in the telecom policy.
The CBI could not have gone ahead with investigations against the telecom minister under the single directive that makes it mandatory for investigators to seek government's permission before investigating a public servant of the rank of a joint secretary and above.
The SC had struck down an executive instruction laying down this rule in the 1997 Vineet Narain judgment. But Parliament enacted a law to gift this shield to themselves, ministers and senior civil servants.
According to sources, the CBI officials were asked to 'help' the Comptroller & Auditor General (CAG), which was looking into the allocation of 2G spectrum.
CBI officials had 'shared' the outcome of their investigations with CAG officials, which was also reflected in the findings of the CAG report.
The government promptly tabled the CAG report in Parliament that indicted the ministry for undervaluing 2G spectrum sold to new players in 2008, forcing Raja to quit on 14 November. The raids at his Delhi and Chennai house followed soon after.