Manhattan District Attorney Cyrus R. Vance Jr. thinks that Zachary Warren might hold the key to understanding the demise of law firm Dewey & LeBoeuf, the American Lawyer reported on Friday. Having left Dewey three years before its demise, in 2012, Warren must have found it odd when Vance’s office called to discuss the firm’s failure. Most people who once worked at the firm would have been surprised, too. They’d never heard of Warren until last week, when he was indicted, along with three more familiar Dewey names: Steven Davis, Stephen DiCarmine and Joel Sanders, the firm’s last chairman, executive director and chief financial officer, respectively. According to the allegations of the 106-count indictment, on or about December 30, 2008 — the end of the first full calendar year of operation following the blockbuster merger of Dewey Ballantine and LeBoeuf Lamb — Warren’s boss, chief financial officer Joel Sanders, allegedly told him that he would receive his full bonus “if the firm satisfied its bank covenants.” The indictment doesn’t say whether Warren knew what that phrase meant.