SAN FRANCISCO — Greenberg Traurig is facing a malpractice investigation by the Heller Ehrman estate, according to Greenberg’s court filings (.pdf) and an attorney representing Heller’s creditors committee.

At issue is Greenberg’s apparent failure to discover that Heller’s biggest creditor, Bank of America, had terminated its security interest in the firm. Lawyers familiar with the matter say that Heller, which retained Greenberg last summer, would have had much better leverage with its banks and other creditors if it had known BofA wasn’t a secured creditor and may have even been able to avoid bankruptcy.