CBI sources said the agency had recovered documents and hard-disks of computers which are being sent to forensic laboratory for further analysis.
The sources said based on the findings of the analysis agency would chalk out the strategy of examination of the accused in the FIR.
They said the agency plans to start the questioning soon.
The sources said CBI will also resort to sending judicial request to Italy, UK, Mauritius and Tunisia to seek details of suspicious transactions which landed in India as alleged bribe money to influence the 3600 crore deal in favour of UK based AgustaWestland.
Former IAF chief S P Tyagi was booked by the agency, along with 12 others, for alleged cheating, corruption and criminal conspiracy in the Rs 3600 crore VVIP helicopter deal and searches were carried out at 14 locations including his residence.
CBI alleged that during his tenure as Air Chief, Tyagi and "with his approval" the Air Force "conceded to reduce the service ceiling for VVIP helicopters from 6000 meters to 4500 meters as mandatory to which it was opposing vehemently on the grounds of security constraints and other related reasons," agency sources said.