After five years of tussling with Goldman Sachs, JPMorgan Chase and the giant hedge fund SAC Capital Advisors, Lorin L. Reisner is ready for a change.
Mr. Reisner, who helped overhaul the Securities and Exchange Commission’s enforcement unit before heading the criminal division of the United States attorney’s office in Manhattan, will soon leave the government for the private sector. He is expected to join a law firm, though it is unclear which one.
Mr. Reisner announced his decision on Wednesday afternoon in an email to the United States attorney’s office, where he has been the criminal division chief since January 2012.
“I have loved everything about serving as chief of the criminal division,” Mr. Reisner, 52, wrote in the email. “The time has come, however, to move on from what I always viewed as, and what has proven to be, a ‘dream’ job.”
Mr. Reisner is the latest prosecutor to spin through the so-called revolving door connecting government service to the private sector, and his departure touched off a management shuffle in the office of Preet Bharara, the United States attorney in Manhattan. In a separate email to staff members, Mr. Bharara announced that his friend and current chief counsel, Joon Kim, would succeed Mr. Reisner. In turn, Daniel L. Stein, a partner at Richards Kibbe & Orbe, will succeed Mr. Kim.
Mr. Kim, a former partner at Cleary Gottlieb, was previously a prosecutor in the Manhattan office, where he convicted Peter Gotti, the boss of the Gambino crime family at the time.
In the clubby world of white-collar crime, Mr. Kim is inheriting a job that carries a great deal of cachet, with the criminal division acting as a main artery running through the United States attorney’s office. Terrorism, cybercrime and Wall Street and public corruption all fall under the domain of Mr. Reisner.
The criminal division job, and the S.E.C. post before it, brought out Mr. Reisner’s aggressive streak, according to lawyers who worked closely with him and spoke on the condition of anonymity. Working under Mr. Bharara, Mr. Reisner helped oversee a widespread crackdown on insider trading. Since Mr. Bharara took office, his prosecutors have filed more than 80 insider trading cases without recording a loss.
Most criminal division chiefs cut their teeth as both assistant United States attorneys and lawyers at New York firms. That was true of Robert G. Morvillo, a prominent New York trial lawyer and one-time criminal division chief, as well as Mr. Reisner’s predecessor as chief, Richard B. Zabel, who is now the deputy United States attorney under Mr. Bharara.
Mr. Reisner, who has bounced between government and private practice, followed the same path.
The son of two public-school teachers, Mr. Reisner grew up in Brooklyn and Spring Valley, N.Y. After graduating from Brandeis University and Harvard Law School — at Brandeis he organized a protest of a paid appearance of G. Gordon Liddy, who helped arrange the Watergate burglary — he clerked for Judge Milton Pollack of Federal District Court in Manhattan.
In 1990, following a stint at Debevoise & Plimpton, Mr. Reisner began his prosecutorial career.
As a rank-and-file prosecutor under Mary Jo White, then a United States attorney, Mr. Reisner earned the moniker “Mr. Right Angles,” a nod to his pristine office and obsession with the tiniest details of a case. “Anal but in an amusing way,” is how one colleague put his meticulous style. Ms. White has called him “one of the best lawyers of his generation.”
He later returned to Debevoise. As a partner at the firm, he handled a mix of white-collar and corporate cases as well as a handful of media clients, including The New York Times.
In 2009, Mr. Reisner moved his family to Washington, where he became the S.E.C.’s deputy enforcement director under Robert S. Khuzami.
Mr. Khuzami and Mr. Reisner engineered an overhaul of the enforcement unit, which had been blamed for missing the warning signs of the financial crisis. As part of the shake-up, they formed a number of specialized units, including a group that focused on complex mortgage products created before the crisis.
That unit generated one of the agency’s biggest cases, a lawsuit that accused Goldman Sachs and one of its traders, Fabrice Tourre, of misleading investors about a mortgage security that eventually imploded. For Mr. Reisner, known for his hands-on management style, the case became a pet project of sorts. He interviewed witnesses and line-edited letters and motions, a task often reserved for lower-level investigators.
“It was very much his case,” said Matthew T. Martens, a partner at Wilmer Hale who was the S.E.C.’s lead trial lawyer in the case against Mr. Tourre, whom a jury found liable for fraud.
Once Mr. Reisner left the S.E.C. to run the criminal division, he worked through a large docket of insider trading cases. During his tenure, the criminal division convicted Rajat Gupta, the former Goldman Sachs director accused of leaking boardroom secrets, and Mathew Martoma and Michael Steinberg, former traders at SAC Capital. The case against SAC, which was founded by the billionaire Steven A. Cohen, culminated last summer with the indictment of the firm itself.
The office also took aim at JPMorgan Chase, extracting a $1.7 billion penalty for essentially turning a blind eye to Bernard L. Madoff’s fraud. And in a deal with Mr. Bharara and other authorities, the giant French bank BNP Paribas is close to pleading guilty to improperly transferring money on behalf of Sudan, a country that the United States government has blacklisted.
Mr. Reisner — who has a daughter in college and a son in high school and whose wife, Mimi, works for the Clinton Foundation — said in his email to colleagues on Wednesday that going forward, “I will be rooting for you enthusiastically from the sidelines.”
Some of those colleagues recalled that, when it came to cases, no detail was too trivial for him. His mantra, they said, was that the headline-grabbing moments are great, but “you have to be willing to wash windows.”