The Securities and Exchange Commission yesterday named two new deputies in its enforcement division, a nod to the unit's mounting caseload and its growing complexity.

Peter H. Bresnan will oversee personnel, training and staffing of the agency's enforcement cases, while Walter G. Ricciardi will handle technology and financial systems. Both men will report to enforcement chief Linda Chatman Thomsen.

In recent years, the enforcement group, which brings civil fraud cases against companies, executives, and professional advisers, has grown by more than 200 lawyers. Agency watchdogs have sued companies from Adelphia Communications Corp. to Xerox Corp. over violations of securities laws and financial misstatements.

Bresnan, 50, led high-profile investigations of former KMart officials and in recent weeks has cracked down on hedge fund Wood River Capital Management LLC. Bresnan has long served as a go-to man at the agency, where he was enlisted to serve as interim chief of the SEC's Boston office after mutual fund trading abuses came to light in 2003. Under Bresnan's oversight, the SEC recovered $420 million for investors in cases against mutual funds Putnam, Massachusetts Financial Services Co., and two FleetBoston subsidiaries.

Bresnan also acted as the lead trial counsel in the SEC's case against WorldCom Inc., in what authorities have called the largest accounting fraud in history.

Ricciardi, 52, made his name in the private sector, working as a top legal official and a member of the board of directors at the accounting firm now known as PricewaterhouseCoopers LLP. Ricciardi joined the SEC in 2004 as leader of its Boston office. He has filed several cases against pharmaceutical companies for making false claims about government approval of drugs. He began his career as a law clerk to U.S. District Judge Charles R. Richey in Washington.