The slip almost created a separation, and prompted Mrs. Murdoch to negotiate more favorable terms for her daughters, according to people close to the couple.

Mr. Zabel, an expert in trust law, is expected to examine the soundness of the trust structure.

“Even with the most sophisticated couple, unless you have perfect 20/20 foresight often some issues can arise that weren’t taken into consideration and are prime for negotiation,” said Paul M. Talbert, a divorce lawyer at Donohoe Talbert in New York, who is not involved in the Murdoch case.

Representing Mr. Murdoch, 82, in the divorce proceeding is Ira E. Garr of the law firm Garr Silpe. But Mr. Murdoch is also relying heavily on the advice of Gerson A. Zweifach, the general counsel of both News Corporation and 21st Century Fox, as the newly separated companies are now known. Mr. Murdoch’s 1998 divorce from his second wife, Anna, cost more than $110 million in cash.

A company spokeswoman has said the divorce will have no effect on either company.

Shortly after a visit to the couple’s Northern California home in June, Mrs. Murdoch returned to New York to learn that Mr. Murdoch had served her with divorce papers, according to several people close to the couple who would not discuss their private matters for attribution.

Mrs. Murdoch, after interviewing about eight different lawyers, including leading members of the matrimonial bar like Robert Stephan Cohen and Peter E. Bronstein, chose Mr. Zabel. Initially, Mrs. Murdoch did not have time to screen potential divorce lawyers and turned to Ms. Sloan, a trusted confidante, by default.

The core of Mr. Zabel’s practice at the law firm Schulte Roth & Zabel is advising wealthy clients like George Soros and the Lehman family, drafting their wills and trusts and advising on estate planning. But he also handles messier matters for his clients; in 2010, for instance, he represented the estate of his longtime client, the Palm Beach philanthropist and investor Jeffry M. Picower, in a $7.2 billion settlement with the federal government over claims related to money that he received from Bernard L. Madoff’s Ponzi scheme.

There is also the occasional divorce assignment. Much of the time, Mr. Zabel will play the role of mediator, and has peaceably settled the divorces of the late author Michael Crichton, the radio host Howard Stern and the New York Jets owner Robert Wood Johnson IV.