WASHINGTON (AP) — Federal regulators say the former CEO of the nation's largest public pension fund conspired with a friend of his to trick a prominent investment firm into paying $20 million in fees to the friend's firms. The Securities and Exchange Commission on Monday filed civil fraud charges against Federico Buenrostro, the former CEO of the California Public Employees' Retirement System, known as CalPERS, and his friend Alfred J.R. Villalobos. Buenrostro denied the SEC's allegations through his attorney.