Here's a 10-point cheat-sheet on the Italian enquiry:
The total deal is worth nearly 4,000 crores. Kickbacks paid of 30 million euros or 217 crores, according to Italian prosecutors.
SP Tyagi, Air Chief Marshall from 2004-2007, allegedly paid by middlemen for the manufacturer via his three cousins, Julie, Sandeep and Dosca Tyagi. The former air force chief has denied the charges.
100,000 euros or 720 lakhs in cash allegedly given to his cousins between 2004 and 2007. No money was transferred in the presence of Air Marshal Tyagi.
Of the 30 million euros allegedly paid in bribes, 20 million was routed through two Switzerland-based intermediaries, Guido Haschke and Carlo Gerosa.
Italian report says payments were made through Tunisia-registered companies controlled by Haschke and Gerosa and were then transferred to accounts in India and Mauritius.
Three companies listed in Italian report as conduits for the kickbacks: IDS Tunisia, IDS India and Aeromatrix.
IDS India does not exist in Indian records.
Aeromatrix was set up in 2009, months before the deal for the helicopters was signed. Its holding company is IDS Mauritius.
The company, headquartered in Chandigarh, bought a contract to provide software solutions to AgustaWestland from another Chandigarh company called IDS Infotech.
Aeromatrix's directors include Guido Haschke and Carlo Gerosa. Its CEO, Praveen Bakshi, has denied any links to the alleged scam and has said he has not been contacted by Italian prosecutors.