Scandals in Palm Beach, Fla., are as much a part of the landscape as Lilly Pulitzer and plastic surgery. In recent years, the wealthy enclave has been rocked by the Bernard L. Madoff Ponzi scheme and the Jeffrey Epstein underage-sex lawsuit, to name just two.
Now you can add a bizarre litigation involving Isaac Perlmutter, the enigmatic billionaire chief executive of the Marvel Entertainment unit of the Walt Disney Company.
Befitting a Palm Beach imbroglio, the dispute began over a local tennis pro. Now, at least three lawsuits later, a neighbor of Mr. Perlmutter has accused him and his wife of sending slanderous letters, unsigned, that say the neighbor "sexually assaulted" an 11-year-old "at knife-point" and murdered a local couple.
The hate-mail campaign, which included more than a thousand letters sent to the neighbor's friends and business associates, is said to be part of an effort by Mr. Perlmutter to pressure the neighbor, Harold Peerenboom, to leave the gated community where they both own homes. One of the letters started, "Today I write you to warn you about Harold Peerenboom of 8 Sloans Curve Road who is a sexual predator."
Mr. Peerenboom, who has never been accused of these crimes, is now trying to compel Marvel to produce Mr. Perlmutter's emails.
A spokesman for Marvel declined to comment, saying it does not discuss personal matters involving Mr. Perlmutter.
The legal soap opera, which has stretched on for more than four years, has played out in courts in Palm Beach and New York, but has gone largely unreported in the national press. This week, a judge in New York state court is expected to take up part of the case that involves Mr. Perlmutter's emails. The court had ordered Marvel to search its computer servers for his emails that mention Mr. Peerenboom. A related hearing is scheduled on Wednesday over what emails were and were not produced.
The case is an example of the strange and sometimes high stakes private legal battles that take place among executives of public companies but that don't always spill into public view.
Such cases raise a thicket of corporate governance questions. There are often disclosure questions surrounding senior executives' health problems. Corporate C.E.O.s including Steven P. Jobs at Apple, Jamie Dimon at JPMorgan Chase and Oscar Munoz at United Airlines have in recent years grappled with how to go public about health problems.
But what's the responsibility of a public company to investigate a controversial private matter involving a senior executive? Does it need to conduct its own inquiry? At what point would it suspend an executive before a ruling is reached? Or should a private legal matter have no bearing on an executive's work?
"If you become a lightning rod, it can negatively impact the company," said Charles M. Elson, a professor of finance and director of the John L. Weinberg Center for Corporate Governance at the University of Delaware. Mr. Elson said that private affairs could lead to distraction at work and could affect the executive's ability to fulfill his responsibilities. "It's very subjective. That's why you have a board."
Mr. Perlmutter has long been a subject of fascination in the media business. Little is known about the reclusive 73-year-old Israeli-American businessman, who sold Marvel to Disney for $4 billion in 2009.
The last public photograph of Mr. Perlmutter was taken in 1985, despite his being Marvel's chief executive and one of Disney's largest individual shareholders. He has never given an interview to the media while running Marvel, despite the Disney unit's influence over American entertainment with its Iron Man, Captain America and X-Men franchises.
Mr. Perlmutter's lawyer, as you might imagine, has denied he had anything to do with the letters. He has contended the case is a shakedown and suggests that Mr. Peerenboom, a Toronto businessman who founded a successful executive search firm, is a serial litigator.
Mr. Peerenboom's side says that the evidence is clear and convincing. His case has withstood multiple efforts to have it dismissed; in each instance, a judge has said that there is enough evidence to proceed.
The story took a particularly strange turn last year when Mr. Peerenboom's legal team said that a private lab had found a direct DNA match on the outside of one of the sent envelopes, implicating Mr. Perlmutter's wife, Laura.
Mr. Perlmutter's lawyers say that the DNA evidence was planted and is inadmissible in court. The lawyers contend that Mr. Peerenboom's legal team stole DNA samples from water bottles and papers that the Perlmutters used and touched during a deposition.
Both sides have hired high-powered lawyers. Mr. Perlmutter retained Roy Black, who helped William Kennedy Smith successfully defend against rape charges in Palm Beach. Mr. Peerenboom hired the New York litigator Marc E. Kasowitz, who has represented Donald J. Trump.
At the center of the case is Karen D. Donnelly, who ran the tennis program inside the Sloans Curve community. She was a favorite of Mr. Perlmutter, an avid tennis player.
Mr. Peerenboom, who moved into the community in 2007, learned that Ms. Donnelly worked without a contract and had not bid for the work, which he claimed amounted to bid-rigging under Florida law. He made his objection to the arrangement known to the homeowners' organization. But the board, nudged by Mr. Perlmutter, overruled Mr. Peerenboom and reworked the agreement with Ms. Donnelly so she didn't have to submit a competitive bid to run the tennis complex.
Ms. Donnelly then filed a lawsuit against Mr. Peerenboom and others — paid for by Mr. Perlmutter — contending she had been slandered.
Then the hate-letter writing campaign began, Mr. Peerenboom says, coinciding with specific efforts to have Ms. Donnelly removed.
Mr. Peerenboom's neighbors in Sloans Curve as well as his business associates in Canada began receiving letters saying Mr. Peerenboom was a child molester. Another claimed he killed Rochelle Wise and David Pichosky, who were found dead from asphyxiation in 2013; that case remains unsolved.
Another batch of letters was sent to inmates of state and federal prisons on stationary purporting to be from Mr. Peerenboom insulting them. Some of the letters included "Hebrew slang and vulgarities," according to a court filing."
On Wednesday, a judge will address the question of whether Marvel must search its servers for evidence of Mr. Perlmutter's connection to the letters.
Last week, Marvel produced some emails, but Mr. Kasowitz said that many others have not been turned over and contended that Mr. Perlmutter was asserting "attorney-client privilege over hundreds of additional responsive emails — even though he claimed to have no control over the Marvel emails in the first place."