Washington, Feb 14: US prosecutors are preparing to bring criminal charges against former Enron Corp. Chief Executive Jeff Skilling, possibly by the end of next week, sources familiar with the investigation said on Friday. Justice Department prosecutors are focusing on the 50-year-old Skilling as the next former Enron top executive to face charges in the two-year-old investigation, the sources said. One source said an Enron-related announcement could come as early as next week, most likely on Thursday, but another source cautioned that the expected charges against Skilling could end up being delayed at the last minute. An attorney for Skilling could not immediately be reached for comment. Enron collapsed into bankruptcy in December 2001 amid revelations the company had hidden billions of dollars in debt and inflated profits to boost its stock price. Enron former Chief Financial Officer Andrew Fastow, who had been indicted on nearly 100 charges, last month pleaded guilty to two fraud counts and agreed to cooperate with prosecutors in exchange for a 10-year sentence. His plea was followed quickly by the indictment of former Enron Chief Accounting Officer Rick Causey, who pleaded not guilty to six felony conspiracy and fraud charges. Prosecutors are preparing to seek an indictment of Skilling from a federal grand jury in Houston, the sources said. The Houston Chronicle, citing unnamed sources, reported on Friday that the charges against Skilling could be brought by a federal grand jury as early as next week. Causey's indictment laid out his alleged role in schemes to mislead investors about the financial condition of the former energy trading giant and noted that he reported directly to Skilling and former Enron Chairman Ken Lay. The sources said that prosecutors did not plan to bring charges against Skilling and Lay at the same time, and said the investigation into Lay's part of the Enron collapse was continuing. Both Skilling and Lay have said they did nothing wrong. Bureau Report