Officials said the agency has sought property details on ten serving and retired officials of the ministry of defence and the Indian Air Force who had handled the procurement process of the AgustaWestland choppers at some point of their service.
It has also sought details from the IT department and the Financial Intelligence Unit to provide details of personal finances, transactions and investments made by some people suspected to have some connection to the case.
They said the references have been made in the light of a hand written note by the alleged middlemen in the case, a document also brought on record by a Milan court which had sentenced Italian defence and aerospace major Finmeccanica's former chief Giuseppe Orsi and the former CEO of the firm Bruno Spagnolini on corruption charges in the sale of a dozen AgustaWestland helicopters to India for VVIP purposes.
Sources indicate ED investigators have made some "analysis" of the probable identity of these code names and hence want to investigate the flow of funds and the "proceeds of crime" and possible kickbacks made in the procurement of these choppers.
With the help of data from the tax department and FIU, some evidence can be established, they said.
To the defence ministry, ED has specified names of officials about whom they need the details of assets possessed.
"This service-maintained data will be matched with current data being provided by the IT and FIU," they said adding some officials of the MoD are in top positions now.
Widening its probe in the Rs 3,600 crore VVIP chopper deal, the ED has also begun a trail of "cash" which is suspected to have been paid as alleged kickbacks for the purchase of these helicopters from UK-based AgustaWestland.
The financial probe agency has set the ball rolling with the second round of questioning of witnesses and accused in connection with the scam.
The ED, in its charge sheet filed last year in a court, had claimed to have detected flow of alleged kickbacks sent from abroad to companies of the accused Gautam Khaitan and cousin brothers of the former IAF chief.
Officials said the flow of funds is being probed as it is alleged that it was quid pro quo to make AgustaWestland eligible to get selected for the final delivery of the 12 AW-101 helicopters to India for VVIP flying duties.
The ED, as per the charge sheet, had traced two payments of Euro 1,26,000 and another two lakh Euros from a company based in Tunisia and others made to Tyagi brothers "camouflaged" in the form of consultancy fee and its probe had found that the said "remittances correspond with the developments taking place in alteration/reduction of mandatory servicing ceiling of the helicopters."
The ED alleged that "besides these two remittances, the Tyagi brothers including the then IAF Chief Tyagi, also received some amount of cash from Haschke and Gerosa.
The ED probe found that the alleged middlemen Haschke and Carlo Gerosa, in collusion with the Tyagi brothers Sanjeev, Rajeev and Sandeep "managed to make inroads in IAF through Air Chief Marshal Tyagi and thereby could influence and subvert the consistent stand of IAF regarding mandatory service ceiling of the helicopters."
This ground was used by CBI and ED to register their respective FIRs in the case and brought out the alleged illegal involvement of the ex-IAF chief and his cousins in perpetrating the scam.
The agency, sources said, suspects the tainted cash could have been used by the accused for making certain high-value payments and purchase of costly items.
It is also expected that a joint team of the two agencies could be authorised by the government to soon travel to few overseas locations to track the trail of funds, both through wire transfer and cash.