text: For years, tenants have worked uneasily inside the Manhattan skyscraper formerly known as the Piaget Building, as federal prosecutors tried to wrest the prime real estate from Iranian-related partners.
  
  The office tower at 650 Fifth Avenue, built in the late 1970s by the Shah of Iran, has been the subject of seizure proceedings by federal prosecutors who contended that the ownership groups engaged in money laundering for their government and also violated economic sanctions imposed against Iran.
  
  Earlier this month, a judge ruled in the prosecutorsâ favor, in what prosecutors described as the countryâs largest-ever terrorism-related forfeiture. The decision, which is likely to be appealed, has only added to the uncertain fate of the building, which is a highly coveted trophy property with notable tenants, like a Juicy Couture flagship store, offices for Starwood Hotels & Resorts Worldwide and the Doris Duke Charitable Foundation.
  
  The governmentâs aim is to sell the property, which brokers said could bring at least $800 million. Proceeds from a sale would probably be used to pay some of the $6 billion in damages claimed by family members of victims of Iranian-sponsored terrorism, including victims of the 9/11 attacks.
  
  The court decision was issued at a delicate time in the strained relations between Iran and the United States, as both sides suggest diplomatic overtures. The new Iranian president, Hassan Rouhani, is in New York this week, as is President Obama.
  
  The buildingâs ownership, under the legal name 650 Fifth Avenue Company, has consisted of the Assa Corporation and Assa Company Limited, which owned 40 percent of the property, and the Alavi Foundation, which owned the remaining 60 percent. The court ruled that the Assa entities are a front for Bank Melli Iran, an institution that is wholly owned by the Iranian government. It also ruled that both Assa and Alavi laundered money.
  
  âThe court has found that, based on the uncontroverted record evidence, Assa was (and is) a front for Bank Melli, and thus a front for the government of Iran,â United States District Judge Katherine B. Forrest wrote in her Sept. 16 ruling.
  
  In the late 1970s, the Pahlavi Foundation, a nonprofit group that was operated by the Shah of Iran to pursue the countryâs charitable interests in the United States, erected the building. It was financed with some $42 million from Bank Melli, which had been lent the money by the Central Bank of Iran, according to court documents. After the Iranian revolution in 1979, the Islamic Republic of Iran sought to take control of the Shahâs property, including the assets of the Pahlavi Foundation, which was renamed the Alavi Foundation.
  
  âAs a former property manager of the building, we never knew exactly who we were working for,â said Michael T. Cohen, regional president for Colliers International. While he managed the building, in the 1980s, Mr. Cohen worked for a predecessor to Colliers International, Williams Real Estate. âWe knew it was the Pahlavi Foundation, and we knew there were people in New York to whom we reported, but beyond that we couldnât be sure of anything.â
  
  As for the organizations leasing space in the building, which included Marc Rich & Company, Pahlavi âwas a murky landlord who catered to murky tenants,â Mr. Cohen said. (Mr. Rich, who died this year, was the financier who fled to Switzerland while under indictment on charges of fraud and illegal trading with Iran, among other charges. His pardon by President Clinton set off a firestorm of criticism.) Ivan F. Boesky, the Wall Street speculator convicted of insider trading in 1987, was also a tenant at one point.
  
  While the government has seized commercial buildings before, the sheer size of 650 Fifth Avenue presented challenges, mostly because of the number of tenants. In 2008, the government first filed a case against Assa, claiming it was a front for Bank Melli. Rents that had been paid to Assa were diverted into an account supervised by the United States Marshals Service. In 2009, the government also began pursuing Alavi. The United States attorneyâs office said on Tuesday that it would request the diversion of Alaviâs rent income as well.
  
  Kathleen A. Roberts, a former judge and a mediator, was appointed by federal court to supervise decisions made by the Alavi Foundation. Ms. Roberts oversaw issues like lease negotiations and building upkeep.
  
  She also supervised the ownerâs decision last year to spend $11 million on capital improvements. The building also hired CBRE to oversee the office space and Cushman & Wakefield to oversee the retail, replacing Jones Lang LaSalle, which had been managing the property. Jones Lang LaSalle did not return calls for comment, and CBRE and Cushman & Wakefield declined to comment.
  
  The United States attorney for the Southern District of New York, which brought the case, declined to comment for the article.
  
  This week, in the aftermath of the court ruling, the government is petitioning the court to make Ms. Roberts the sole decision-maker over the property. That request could raise some additional concerns for tenants already bedeviled by unknowns, real estate experts said.
  
  Gary M. Rosenberg, a founding partner at the law firm Rosenberg & Estis, suggested that a government landlord might act more slowly than a private one.
  
  âIf tenants need something outside the four corners of the lease â for example, a fire knocks out the elevators â a typical landlord would call the insurance company and then call the elevator company and say, âJust fix it,âÂ â he said. âThe government isnât going to pay to get the elevators fixed until they get their insurance proceeds.â
  
  Because of the expected appeal, Ms. Roberts will most likely continue to oversee the building, and any sale will probably be a few years away.
  
  But even talk of a potential sale of this property, at the corner of Fifth Avenue and 52nd Street, generates a lot of excitement in the real estate industry.
  
  âIt is right in the heart of the most expensive retail real estate in New York City,â said Robert K. Futterman, chairman and chief executive at the retail brokerage RKF. He added that âif it is put on the market, we are going to see an exciting bidding war from all the major retail players.â
summary: An office tower built in the late 1970s by the Shah of Iran is coveted real estate that could be sold after a judge found that its owners laundered money for Iranâs government.