The CBI has questioned former Mumbai Police commissioners Sanjay Pandey and Param Bir Singh in connection with Rs 100 crore extortion allegations against former minister Anil Deshmukh, officials said on Monday. Pandey, who retired on June 30, is facing two CBI FIRs -- illegal interception of phones of NSE employees by iSec Services Private Ltd, a company founded by him, and violation of SEBI guidelines in conducting NSE's system audit.