MIAMI — New York and South Florida lawyers spent the weekend fielding calls from panicked clients who lost millions in a $50 billion alleged fraud linked to Manhattan investment adviser Bernard Madoff.

Some of the lawyers said there is little chance of getting the money returned from Madoff, and they are looking at third parties to sue, such as financial advisers and institutional investors. However, the first class action in the case, filed in the Eastern District of New York, targets both Madoff and other financial entities to be determined at a later date. Keller v. Madoff, Bernard Madoff Securities and John Does 1-100, No. CV808-5026 (E.D.N.Y.).

Mark Mulholland of Ruskin Moscou Faltischek in Uniondale, N.Y., filed the class action on Friday on behalf of Irwin Keller, a New Yorker who invested $2.5 million with Madoff. Mulholland said he and his partners have interviewed 100 other potential plaintiffs from Argentina, Canada, Europe and throughout the United States.

“One category to target is institutional investors who may have been afforded a more graceful exit,” said Mulholland. “If we can identify a handful of institutional investors … who were made whole and even made a profit before the house of cards collapsed, that’s going to be something we will focus on.”

Michael Tein of Lewis Tein in Coconut Grove, Fla., is also looking to target third parties.

“We’re going to be as aggressive as possible in pursuing third-party liability to the extent that we can,” said Tein. Tein and his partner, Guy Lewis, are representing investors from South American and Manhattan who had invested $20 million with Madoff, including one client who invested $11.5 million. He declined to name the clients.

“I am very pessimistic about the ability to recover the investment itself,” Tein said. “But the fraud is too big for there not to be a problem with banks, brokerage houses, clearinghouses and third party fiduciaries. It’s not as if this gentleman kept all his money in-house.”

Madoff, who lives in Manhattan and Palm Beach, Fla., was sued for securities fraud on Dec. 11 after allegedly telling his sons, who work for him, that his investments business was a fraud and a Ponzi scheme. The U.S. Securities and Exchange Commission is estimating the loss at $50 billion, and investors include banks throughout the world, charities, hospitals and some of the wealthiest individuals in the country.

Madoff’s arrest has sent shock waves through Wall Street, Palm Beach and financial markets around the world.

Last Thursday, a federal judge in New York froze Madoff’s assets and appointed a receiver to the case, Lee Richards, a lawyer at New York-based Richards Kibbe & Orbe.

Richards, who concentrates his practice on white-collar defense, famously represented Jack Grubman, who was once Wall Street’s top telecom analyst but was banned for life from the securities industry in 2002 after the WorldCom scandal.

Richards did not return calls for comment.

Mark Raymond, the Miami-based managing partner of Broad and Cassel, also has “numerous” clients who invested with Madoff and lost “tens of millions” of dollars. The clients lost 60% to 70% of their net worth. “I’ve heard of instances where trusts of the infirmed and Alzheimer’s patients were in this fund,” Raymond said. “This is the granddaddy of all Ponzi schemes.”

Like Tein, Raymond — who served as receiver to one of the largest Ponzi schemes ever in 1985 — is looking for third parties to sue. “We’re identifying the persons who may have responsibility in this — persons who were promoters, financial advisers and other hedge funds,” Raymond said. “We’re looking at what due diligence did they do or not do.”

Raymond also said that Madoff’s personal assets, while likely substantial, will not be sufficient for defrauded investors.

Another avenue of recovery for the receiver will be redemptions — recovery of funds from investors who closed their accounts in recent years. Raymond guessed that the receiver has 20 to 30 lawyers working on the case. “Investigative and legal fees to unwind this behemoth will be gargantuan,” he said, adding that it will likely take three to five years to unravel the case.

Martin Press, a partner at West Palm Beach, Fla.-based Gunster Yoakley, said that the local accountants for Madoff could also be a target of investors, although their insurance is likely capped at $5 million each. The fact that three local solo accountants and not large accounting firms were responsible for auditing all of Madoff’s billions of investments would be a huge red flag, said Tein.

“I can’t imagine a larger or more vibrantly colored red flag than funds of this magnitude being audited by fly-by-night, flea-sized public accountants,” he said. “I just wish my clients had told me about this investment two weeks ago.”

The Securities Investor Protection Corporation (SIPC), which maintains a special reserve fund authorized by Congress to help investors at failed brokerage firms, announced Monday that it is liquidating Bernard L. Madoff Investment Securities under the Securities Investor Protection Act (SIPA).

The United States District Court for the Southern District of New York granted the application and appointed Irving H. Picard as trustee for the liquidation of the brokerage firm, and further appointed the law firm of Baker & Hostetler as counsel to Mr. Picard.

Picard’s job will be to similar to the receiver’s — to locate any assets of Madoff and return them to customers as quickly as possible.