Environmental energy company USA Synthetic Fuel Corp. revealed that the Securities and Exchange Commission is investigating the company after it modified its financial statements for all of 2012 and the first quarter of 2013, according to a regulatory filing with the agency on Tuesday.

USA Synthetic Fuel received a subpoena from the SEC’s Division of Enforcement in July, in which the agency sought to obtain documents and information related to the company’s accounting practices and internal controls, the filing said. In addition to changes made to the company’s financial statements, the SEC is looking to investigate the resignation of the KWCO, PC accounting firm as Synthetic Fuel’s independent auditor in January 2011, its reinstatement in March 2013, and then its dismissal in June 2013.