First time arrest of a military chief
The arrest of Indian Air Force former chief Air Chief Marshal (ACM) S.P. Tyagi by the Central Bureau of Investigation is the first instance of a serving or retired military chief being arrested on charges of corruption. The CBI arrested ACM Tyagi, his cousin Sanjeev Tyagi and lawyer Gautam Khaitan in connection with the purchase order for VVIP helicopters in 2010 for the IAF. 

Allegations by CBI
The CBI said they were arrested for alleged irregularities in the procurement of a dozen AW101 VVIP helicopters from U.K.-based AgustaWestland, part of the Italian consortium Finmeccanica. 

The CBI claims that ACM Tyagi “entered into criminal conspiracy with other accused persons and in 2005” to change the service ceiling of VVIP helicopters from 6,000 m to 4,500 m, to make AgustaWestland eligible to participate in the tender. Twelve per cent of the total deal of Rs.3,767 crore is alleged to have been the commission involved. 

After the allegations first emerged in Italy, an embattled UPA government had moved swiftly to order an investigation in February 2013. The case was handed over to the CBI and the Enforcement Directorate, which have relied substantially on evidence from Italian courts. 

Past allegations against military chief
1.  In 1987 the central investigation agencies had raided Admiral S.M. Nanda, accusing him of being a middleman in the sale of German-made HDW submarines to India in the early 1980s. Two decades later the case was formally closed by the CBI, saying no concrete evidence was available. 
2.  In 2006 the CBI filed an FIR alleging kickbacks in the purchase of the Barak missile system from Israel, naming among others Admiral Sushil Kumar. Seven years later the CBI told a Delhi court it couldn’t find any evidence. 

Way forward
In this case, the Indian hand in the deal has been corroborated by an Italian court. But a case is only as good as its conclusion. And defence deal investigations have a habit of getting complicated by the difficulties in securing the kind of evidence that is required to secure firm convictions. How this case, which has significant political ramifications, plays out, remains to be seen.