Federal prosecutors in the Enron investigation may be close to filing a new round of criminal charges stemming from a series of off balance sheet transactions that Citigroup ( C) had a role in arranging, according to a recent court filing. The new charges, which prosecutors reportedly said they are contemplating filing within the next several weeks, involve a deal called Yosemite, which involved a series of controversial prepaid oil-and-gas trades between Enron and Citigroup. The Yosemite transactions, which were the subject of a high-profile congressional hearing last summer, have stirred controversy because critics contend the deals were really "disguised loans" to Enron. The Yosemite deals helped provide nearly $3.8 billion in financing for Enron, yet they never appeared as a debt on the energy trading firm's books. Lawyers for former Enron treasurer Ben Glisan raised the possibility of the new charges being filed in a motion to the judge overseeing the Enron prosecution. Earlier this month, Glisan was indicted on fraud charges, along with Enron's former chief financial officer Andrew Fastow, over his alleged involvement in other questionable Enron transactions. A Citigroup spokeswoman declined to comment on the Glisan filing. A Justice Department spokesman could not be reached for comment. The Glisan filing makes no specific mention to Citigroup or whether charges are being contemplated against any parties. But last month, in a conference call with reporters, Citigroup officials said they were close to reaching a settlement with the Securities and Exchange Commission, which has been investigating the bank's role in the Yosemite deals and other Enron matters. Citigroup, meanwhile, is being sued by a number of mutual funds that purchased bonds that were used to help fund the Yosemite transactions. Citigroup, however, is not the only Wall Street firm that has run into problems over its dealings with Enron.