The embattled hedge fund SAC Capital Advisors is bracing for investors to pull out as much as several billion dollars by a deadline today, the New York Times DealBook blog reported today. Withdrawals have stepped up as a separate deadline looms for law enforcement officials investigating the firm. Over the next several weeks, the authorities must decide whether to bring a criminal case against SAC related to suspicious trading in two drug stocks. The government has already brought charges against a former SAC employee connected to those trades, which involved the fund’s billionaire founder, Steven A. Cohen. Authorities have explored new avenues on how they might bring a criminal case against the firm and possibly a civil action against Cohen. The escalated investigative activity has caused SAC investors to grow increasingly worried about the fund’s future. Already this year, investors have pulled $1.7 billion from the $15 billion fund, or about a quarter of the outside money managed by SAC.