Hertz’s single-year restatement announcement in June has mushroomed into a multi-year restatement and an investigation by the Securities and Exchange Commission, the company reported in an Form 8-K filing on Friday, which offered the company’s first hints that the problems may stem from poor tone at the top.

Hertz said in June it found problems in four specific accounting areas and needed to restate 2011 financial statements, with adjustments possible to 2012 and 2013 financial statements as well. Now Hertz says it will restate 2012 and 2013 results and is cooperating with an SEC investigation, which launched in June. “The company has and intends to continue to cooperate with the SEC in its investigation,” Herz said.

Errors found so far add up to a reduction in net income attributable to Hertz of $87 million spread across the three years, Hertz said in its latest 8-K, although the investigation is not complete and the numbers could still change. The company does not expect to complete its internal review and file new financial statements until at least mid-2015, and makes no promise that it has gotten to the bottom of the problem. “There can be no assurance that the process will be completed at that time, or that no additional adjustments will be identified,” the company wrote.

Hertz said its internal investigation is being conducted under the direction of its Audit Committee with the assistance of independent counsel, “and has been looking into the tone at the top influence and the involvement and oversight that members of the Hertz organization may have had on those potential errors.” The company said its review of the initial matters identified for investigation is “substantially complete, although follow-up investigative work on related matters is ongoing.”

The company initially identified accounting errors in capitalization and timing of depreciation for certain non-fleet assets; allowances for doubtful accounts in Brazil; allowances for uncollectible amounts with respect to renter obligations for damaged vehicles; and restoration obligations at the end of facility leases. In its update, Hertz says the most material errors remain in these four areas. The company also expected an adverse opinion on internal control as a result of the issues.

Hertz has seen some significant leadership change in tandem with the restatement announcements. In October 2013, CFO Elyse Douglas resigned, following the Hertz announcement in May 2013 that the company was moving its headquarters from New Jersey to Florida, a move Douglas said she could not make for personal reasons. Thomas Kennedy assumed CFO duties in December 2013, along with a new chief accounting officer who began in mid-May and a new vice president of SOX compliance who began in late April, shortly before the restatement news surfaced.

Then in September, with the restatement investigation well under way, CEO Mark Frissora resigned and Hertz struck an agreement with investor activist Carl Icahn to eject three long-time board members to make way for Icahn picks. Interim CEO Brian MacDonald remains in that role while a five-member search committee, including two of Icahn’s appointments, searches for a permanent CEO. Icahn, who owns 8.5 percent of Hertz’s stock, said in August he wanted to explore issues “relating to shareholder value, accounting issues, operational failures, underperformance relative to its peers and…lack of confidence in management.”