NEW YORK ( TheStreet) -- Susan Merrill, the head of enforcement at the Financial Industry Regulatory Authority, is stepping down, the Wall Street Journal reports. Merrill hasn't set a departure date from Finra, Wall Street's self-regulatory body, people familiar with the matter said, the Journal reports. Merrill has a spotty record as enforcement chief, the Journal says. She helped merge the enforcement departments of the National Association of Securities Dealers and the New York Stock Exchange, and brought a number of auction-rate-securities cases against Wall Street firms. But she also failed to uncover Bernard Madoff's Ponzi scheme. It's not known who will succeed Merrill, the Journal reports. -- Reported by Joseph Woelfel in New York. Follow TheStreet.com on Twitter and become a fan on Facebook.