Robert Khuzami, who led the U.S. Securities and Exchange Commission's enforcement division's pursuit of financial industry wrongdoing related to the subprime crisis, plans to step down as early as next month, three people with knowledge of the matter said.

Khuzami, 56, notified SEC Chairman Elisse Walter of his decision earlier this month, according to the people, who asked not to be identified because the matter isn't public. Walter has yet to choose a replacement, the people said.

Then-Chairman Mary Schapiro hired Khuzami in 2009 to help restore the agency's image after it was battered for missing Bernard L. Madoff's Ponzi scheme. He carried out the biggest shakeup in the enforcement unit's history, eliminating layers of management, expanding investigators' legal powers and creating five specialized units to police Wall Street.