An investigation into allegations of misconduct and financial problems at the Screen Actors Guild — Producers Pension and Health Plans has found that the accusations are mostly baseless.

In a letter to plan participants posted Thursday on the plans’ website, the plan trustees — who are SAG and industry reps — asserted that “an extensive and independent investigation” has found no validity to the allegations by fired plan exec Craig E. Simmons.

“Based on the results of the investigation, we can assure you that the fiscal integrity of the SAG-PPHP remains sound and your benefits are secure,” the letter said. “In plain English, your pension plan is safe; your health plan is safe.”

Simmons has filed a complaint with the federal government asserting that he was terminated for acting as a whistleblower about alleged embezzlement at the fund. The board of trustees of the plans, operated separately from SAG, denied the allegations in September and retained outside counsel to review the matter.

Simmons alleged in a complaint filed with the U.S. Labor Dept. that he was fired in March by chief executive Bruce Dow due to Simmons’ refusal to mislead board trustees and government investigators about embezzlement by the plans’ former chief information officer, Nader Karimi. Simmons also alleged in the complaint that Dow and other execs had misused funds for personal benefit.

“The independent investigator found that most of Mr. Simmons’ allegations are false, including his claims that Mr. Dow is antigay, that he caused the plans to improperly reimburse health expenses for his wife, that he caused plan employees to work on his home and perform personal chores for him, that he promoted employees who were unqualified and that he instructed staff to mislead U.S. Dept. of Labor auditors. These findings presented by the independent investigator were reviewed by PricewaterhouseCoopers’ forensic auditors.”

The trustees also addressed embezzlement of $2 million that was discovered three years ago.

“As to Mr. Simmons’ claims of financial mismanagement, while it is accurate that the trustees discovered in 2008 that approximately $2 million had been misappropriated by a then-plan employee, the plans investigated the matter immediately, engaging forensic auditors and legal counsel,” the letter said. “The matter was successfully resolved earlier this year, and substantially all of the misappropriated funds were recovered from our insurance company. Plan assets were not materially affected.”

The trustees also said that they are evaluating whether remedial actions are required.

“The trustees are committed to carrying out our fiduciary and ethical obligations and are now engaged in a full review of the plans’ internal operational controls,” the letter said. “We have created a special subcommittee of the board with its own independent counsel to review the plans’ policies and guidelines to ensure that they remain current with best practices.”

The SAG health plan covers about 40,000 participants and has assets of more than $2 billion, while the retirement plan pays pensions to an estimated 9,000 beneficiaries. The plans announced in October that, due to tough economic times and a drop in TV earnings, they had been forced to tighten eligibility requirements and benefits, along with warning members that further cuts could be coming.

Thursday’s letter from the trustees did not identify the investigator, asserting that the person was “highly regarded” and “independent.”

The letter was posted 11 days after a group of SAG members have been circulating a letter that questions the probe. Several hundred members have since signed an online petition.

The letter from the members identifies the investigator as Nancy Solomon. The letter asserts that Solomon is a friend of SAG national exec director David White and that the two previously had worked together at the law firm of O’Melveny & Myers.

“Due to these close associations, we have serious concerns that Ms. Solomon’s objectivity and due diligence may have been compromised, resulting in the cherry-picking of certain people to interview while overlooking others who may not have been as supportive of Mr. Dow,” it said.

The letter also takes issue with the trustees for not disclosing the insurance settlement earlier and asserts that trustees had not addressed Simmons’ allegations.

“Your fiduciary responsibility is to protect this fund which, after all, is the members’ money,” it said. “We feel you have not properly addressed these wrongs nor have you been forthright in communicating with us.”