Correction, 5/4/12, 9:47 a.m. EDT: The original version of this story incorrectly identified Wells Fargo as one of the four banks to which Dewey & LeBoeuf owes a combined total of $75 million against a $100 million line of credit. The banks in question are Bank of America, Citi Private Bank, HSBC, and JPMorgan Chase & Co. The tenth and eleventh paragraphs of the story have been revised to include the correct information. We regret the error.

In the latest blow to the reeling Dewey & LeBoeuf, the Manhattan District Attorney’s Office has opened an investigation into “allegations of wrongdoing by our former chairman, Steven Davis,” and the firm has tapped two of its own lawyers to lead an internal probe, according to a memo authored by Dewey management and obtained by The Am Law Daily.

The unsigned, two-paragraph memo, sent by the firm’s office of the chairman to partners worldwide late Friday, states that Dewey leaders learned of the D.A.’s investigation earlier in the day and responded by asking partners Harvey Kurzweil and Seth Farber to act as counsel to the firm as it conducts its own inquiry.

The memo closes by saying, “In addition, we have been in contact with the District Attorney’s Office and have told the District Attorney’s Office that the Firm intends to cooperate with that Office’s investigation,” and telling partners to direct any questions to Kurzweil, Farber, or Dewey general counsel—and New York partner—Janis Meyer.