The arrest of former Indian Air Force chief S.P. Tyagi in the Rs 3,767-crore AgustaWestland helicopter deal case has dented the IAF's reputation of being a professional force, Air Chief Marshal Arup Raha said here on Saturday."It is very unfortunate that such an episode has taken place. It does dent our reputation as a professional force," Raha said while interacting with reporters on the sidelines of a programme at the Netaji Subhas Chandra Bose International Airport."But we believe in the rule of law. I am sure every Indian citizen believes in the rule of law. The due process is on. Whatever is the final verdict, we will go by that," Raha said.A court in New Delhi on Saturday sent Tyagi to CBI custody till December 14.Metropolitan Magistrate Sujit Saurabh allowed the Central Bureau of Investigation to quiz Tyagi, his cousin Sanjeev Tyagi alias Julie Tyagi and Delhi-based lawyer Gautam Khaitan till December 14.The former IAF chief -- the first chief of any wing of the armed forces to be arrested in the country -- and the others were allegedly involved in irregularities in the procurement of 12 AW-101 VVIP helicopters from Britain-based AgustaWestland.