Yeshiva University is trying to determine whether it was among countless investors whose savings may have been wiped out in a $50 billion Wall Street investment swindle that may be the largest in history. Jewish financier Bernard L. Madoff, a legendary investor and longtime university trustee who was the its treasurer and chairman of its business school, was arrested at his Manhattan apartment Thursday on a single count of securities fraud, after being turned in by family members. According to federal prosecutors, Madoff told two senior employees on Wednesday that he had been operating a "giant Ponzi scheme" in which he paid investors out of new funds received from other clients, not from investment returns. Madoff allegedly described his firm's stellar investment returns as "all just one big lie," saying he had been insolvent for years, and estimated his losses at $50b. He said he had as much as $300 million he intended to distribute to relatives and some investors before turning himself into authorities. The employees had approached Madoff, 70, after noticing he had appeared "under great stress" in the wake of investor calls for approximately $7b. in asset redemptions amid the economic crisis - money Madoff allegedly told his employees did not exist. The firm was understood to have between $8b. and $15b. under management, according to prosecutors. Madoff was released Friday on $10m. bond after reaching a deal with US regulators to freeze his company's existing assets and place them under the supervision of an independent receiver. At least one Jewish charity, the Boston-based Robert I. Lappin Charitable Foundation, shut its doors and terminated its entire staff Friday after its assets - entirely managed by Madoff's company - were frozen. "It is with a heavy heart that I make this announcement," said Robert I. Lappin, the foundation trustee, said in a statement. "The foundation's programs have touched thousands of lives over many years in our efforts to help keep our children Jewish." Yeshiva University officials would not comment on the degree to which its endowment funds may have been affected. "We are shocked at this revelation," said Hedy Shulman, the university's director of media relations. She said Madoff had resigned all his positions with the university. "Our lawyers and accountants are investigating all aspects of his relationship to Yeshiva University. We reserve our comments until we complete our investigation," Shulman said. The university is private. Lawyers for distraught investors worried they had lost all their savings packed a courtroom in the federal building Friday, awaiting a hearing on the disposition of Madoff's remaining assets. The hearing was canceled after the agreement to freeze his company's assets and appoint the receiver. The deal, agreed to separately by Madoff and his company, was approved later in the day by a federal judge, said Alexander Vasilescu, trial chief of the federal Securities and Exchange Commission. Vasilescu said the receiver would secure the assets, funds and location of Madoff's businesses to preserve assets and "determine the scope of the misconduct." Stephen A. Weiss, who said he had spoken to at least 30 investors, said many of them were devastated. "They were living comfortable lives and serene retirements, and by the late afternoon their lives were thrown into a spiral of horror," Weiss said. "These people are panicked. These people are sorrowful. These people are angry. And many are now destitute." One investor, Lawrence Velvel, 69, dean of the Massachusetts School of Law, said he and a friend may have lost millions of dollars between them. "This is a major disaster for a lot of people," Velvel said in a telephone interview from his Andover, Massachusetts, office. "You work all your life, you finally manage to save up something, and somebody who's entrusted with it, it turns out suddenly he's a crook. Lots of people are getting fully or partially wiped out." Velvel said he wants to know where government regulators, as well as accountants and others at Madoff's company, were when the money was being lost. The complaint said Madoff handled investments for as many as 25 clients in his private investment business, but lawyers for investors Friday said the number likely runs much higher. Some estimates ran into the hundreds. Sterling Equities Inc., an investment firm run by New York Mets owner Fred Wilpon, acknowledged in a statement Friday that it had investments with Madoff's firm. "We are shocked by recent events and, like all investors, will continue to monitor the situation," it said. Madoff's lawyer, Dan Horwitz, said his client was "a long-standing leader in the financial-services industry with an unblemished record" and would "fight to get through this unfortunate event." Vasilescu said it was "way too premature" to assess how much money investors might get back. He said a central job of the receiver would be to assess claims and ultimately to plan how assets can be distributed. Madoff, a former Nasdaq stock market chairman, founded his firm in 1960, using $5,000 he earned in part as a lifeguard on Long Island beaches. In the industry, he had a reputation for safe investments and steady returns that made individual investors eager to place their money with him and made competitors suspicious of his success. Marc Powers, a former SEC enforcement branch chief and head of the securities practice at Baker Hostetler, said Madoff was "a very well respected, highly regarded person" on Wall Street. "Everybody heard of him," he said, noting his firm had received calls from investors Friday worried about their future. "There's a shell shock that's going on now. This ruins people's lives. It destroys whatever they built up over 40 years, at the hands of a person they trusted." Velvel said he listened to Madoff's employees explain how the firm made profits in good times and bad through computerized trading on blue chip stocks and options, enabling small and steady profits on scores of trades. "It made all the bloody sense in the world," he said. "The way we understood, they never went for the big hits. If you take a percent here, a half-percent there, this can add up to what Madoff was saying." AP contributed to this report.