Hyderabad, Oct 03: A high-level inquiry into Wednesday's naxal attack on Andhra Pradesh Chief Minister N Chandrababu Naidu's convoy began today with security expert C Subrahmanyam holding detailed discussions with officials at Tirupati. Subrahmanyam, a retired IPS officer, is likely to submit his report in a day into the attack in which Naidu, his cabinet colleague Gopal Krishna Reddy, two TDP MLAs and the car driver were injured. During discussions with officials, Subrahmanyam took stock of the events that occurred before and after the blast, the nature of attack and the methodology that was adopted, official sources said. Subrahmanyam had served in the Prime Minister's security wing in early '90s. Bureau Report