U.S. prosecutors have requested that the Securities and Exchange Commission continue to delay its case against billionaire hedge fund investor Steven Cohen because criminal cases against his former employees have not yet been closed.

In a letter sent to SEC Judge Brenda Murray, U.S. attorney in Manhattan Preet Baharara said that his office’s criminal cases coincide with the SEC’s civil case against Cohen. Cohen, who created Point72 Asset Management—previously known as SAC Capital Advisors—is facing SEC charges for failing to properly supervise his employees, including two portfolio managers, Mathew Martoma and Michael Steinberg, who were allegedly involved in insider trading, the letter said. Prosecutors have asked that the SEC hold its case against Cohen until Martoma’s and Steinberg’s are resolved.