Official sources said the summons to Tyagi have been issued under the provisions of the Prevention of Money Laundering Act (PMLA).
The ED had registered a PMLA case in this regard in 2014 and named 21 people, including Tyagi, in its money laundering FIR.
Here is a short timeline of Tyagi's alleged involvement and how things have progressed.
1) First meeting:
According to reports, it was in 2004 that a representative of Finmeccanica, AgustaWestland's parent company, first met Tyagi
, who was then the IAF vice-chief.
2) Tyagi's involvement deepens:
According to an agency report, just months after the government announced that Tyagi would be the next IAF chief, in January 2005, Guido Haschke and Carlo Gerosa, the two out of three alleged foreign middlemen in the scam, met him again
It was during his meetings with these middlemen that Tyagi changed the specifications of the prospective VVIP chopper.
3) Tyagi's Italy visits:
Tyagi's visits to Italy, twice after his retirement, are also under the scanner of the CBI.
According to reports, it has not been ascertained whether he met any of the alleged middlemen in the scam during these trips.
4) The initial rumblings:
According to a Times of India
report, the investigating agencies have found that Tyagi was in Milan, Italy, in 2012, allegedly to meet Haschke and Gerosa.
Tyagi's Monday interrogation has thrown up more details about his trips and meetings.
According to the ToI report, during his 2012 Milan trip, Tyagi was "really agitated" about the probe being conducted by Italian authorities into the matter.
Citing documents shared with India by Italy, the report says that Tyagi, referred to as "Giuli", was in Haschke and Gerosa's company at the Milan-Malpensa airport on March 25, 2012.
5) The lid is blown off:
On February 12, 2013, the Italian police arrested Giuseppe Orsi, the head of defence group Finmeccanica SpA, the parent company of AgustaWestland, on a warrant alleging that he had paid bribes to win the Indian VVIP chopper deal contract, reported Reuters
This, and the subsequent Indian and Italian investigations into the matter, spelt the beginning of Tyagi's troubles.
6) Tyagi's name pops up:
In March, 2013, the CBI said that it had found evidence against Tyagi
that suggested that he had extended favours to AgustaWestland by changing specification requirements for the VVIP choppers. The agency registered a first information report (FIR) against Tyagi, besides 12 others.
The FIR also named three of Tygai's relatives — Sanjeev, Rajeev and Sandeep.
Even as the CBI registered the FIR, reports said that the agency's preliminary inquiry had revealed one of the middleman in the deal, Haschke, had entered into several consultancy contracts with AgustaWestland through his Tunisia-based company Gordian Services Sarl. Between June 2004 and March 2005, he made two remittances – of euro 126,000 and euro 200,000 – in close succession, to Tyagi's brothers, in the name of “consultancy contracts”.
7) The ED turns on the heat:
Sources said that the properties attached under the provisions of the PMLA are located in and around the national
capital region and the estimated book value of the assets is about Rs 7 crore.
8) AgustaWestland and Tyagi back in focus:
In April this year, the Milan Court of Appeals — equivalent of an Indian High Court — gave details of how alleged bribes were paid by helicopter-maker Finmeccanica and AgustaWestland to Indian officials through middlemen to clinch the deal.
According to an Indian Express
report from April, 2016, the Italian Court of Appeals has observed that there are “unmistakable indications regarding corruption of an Indian officer”.
The observation pointed at then Air Chief Marshal Tyagi.