New York Attorney General Eliot Spitzer (search) said on Monday he expects to reach a "civil resolution" with American International Group Inc. (AIG), calming fears that his investigation could lead to criminal charges against the insurance company.

Along with the Securities and Exchange Commission (search), Spitzer for months has been looking at AIG's accounting, ranging from a deal it struck with Warren Buffett's Berkshire Hathaway Inc. to transactions with offshore reinsurers.

"The board and current management of the company are now cooperating with this investigation," Spitzer said. "Based upon these efforts, and based upon our knowledge to date, we believe that a civil resolution with the corporation will ultimately be achievable."

Spitzer's statement came as a welcome relief to AIG investors who have seen some $57 billion in stock-market value wiped away over the past six weeks. Shares closed 4.6 percent higher, or $2.35, at $53.30 on the New York Stock Exchange (search).

"There had been some speculation that there could be a criminal investigation against the company," said Hilary Hayes, a portfolio manager of Victory SBSF Capital Management in New York. "Any criminal investigation would have been a major hit to AIG."

Even as the threat of criminal charges appeared to diminish on Monday, there remained a host of unanswered questions about AIG. In addition to its accounting, one area that has raised concerns is AIG's relationship with Starr International Co., a privately held company that owns about 12 percent of AIG's stock and acts as a compensation vehicle for its top managers.

AIG executives have traditionally sat on the board of Starr and its largest stakeholder has long been Maurice "Hank" Greenberg, the recently ousted AIG Chairman and CEO.

But a number of AIG executives, including new CEO Martin Sullivan, have now left the board, AIG said on Monday -- possibly assuaging some worries about conflicts of interest.

Greenberg remains the largest owner of Starr, however, and therefore could still have a hand in compensation decisions for AIG unless the structure is changed.

AIG and Greenberg are discussing a possible new structure for Starr that would eliminate the former chairman's influence over AIG executives' paychecks in the future, the Wall Street Journal reported on Monday.

The probe of AIG has also spread to Ireland, where regulators confirmed they have been working with U.S. authorities "for some months" examining the deal involving AIG and a unit of Berkshire Hathaway's General Re that has an office in Dublin.

In remarks prepared for a speech this week, Irish Financial Services Regulatory Authority Chief Executive Liam O'Reilly says he is "actively engaged" with the General Re unit and working to ensure "necessary corrective actions are taken."

AIG -- which last week announced the resignation of Greenberg, delay of its annual report and discovery of improper accounting -- over the weekend disclosed it learned of efforts to remove documents from its Bermuda building.

Sullivan said the insurer alerted investigators of the incidents.

"We have been working closely with regulators and other authorities to ensure that everyone throughout the organization complies with AIG's policy of full cooperation with all investigative efforts," Sullivan said.