Patiala House Court on Saturday granted the Central Bureau of Investigation four-day custody of former Indian Air Force chief Shashindra Pal Tyagi. Tyagi was arrested on Friday along with Delhi-based lawyer Sanjeev Gautam Khaitan and Sanjeev Tyagi for allegedly accepting kickbacks to influence the purchase of 12 VVIP AgustaWestland helicopters. The CBI said the deal was worth Rs 3,767 crore, of which 12% was paid in bribes.

SP Tyagi has continued to deny all allegations made against him. On Saturday, he said the decision to purchase the helicopters was a collective one. His counsel also claimed that it was the Prime Minister’s Office that had recommended changing the ceiling height of the VVIP choppers, which was allegedly modified so that AgustaWestland could get the contract.

These were the first arrests made in the case.

Investigators said that the company was shown undue favour in connection with the deal. They also said that their investigation has revealed that AgustaWestland accepted illegal vendors through middlemen and relatives of the former IAF chief, including Sanjeev Tyagi. The three accused had been arrested under Section 120B and Section 420 of the Indian Penal Code and Prevention of Corruption Act, 1988.

The agency has been investigating SP Tyagi along with his associates and middleman Christian Michel in connection with the case. In May, the CBI said that two “suspicious” payments were made to accounts held by the former Air Force chief. The agency also learnt that SP Tyagi was an owner or shareholder of at least five different companies. He retired from his post in 2007.

In July, the Centre told the Supreme Court that a chargesheet in the case was likely to be filed by the end of the year. The AgustaWestland helicopter deal, which snowballed into a huge controversy, is related to an agreement signed in 2010 to buy 12 helicopters from the British-Italian firm. The Congress-led United Progressive Alliance government was in power at the time.

The deal was put on hold after Italy arrested the head of Finmeccanica, AgustaWestland’s parent company. The CBI had registered a case against the former IAF chief and 13 others, including Tyagi’s three cousins and Michel.