On July 31, 2008, Guido Bertucci, the top official in a U.N. department charged with promoting good governance around the world, retired in disgrace.

An internal U.N. investigation found that he committed "gross negligence" in handling a $2.8 million trust fund donated by the Greek government, and suggested that Bertucci might be held "personally accountable and financially liable" for the misspent funds, many of which went for purposes unrelated to the intended project.

Secretary General Ban Ki-moon handed the Bertucci case over to a U.N. disciplinary committee just two days before Bertucci's retirement — too late to do anything that would affect his retirement or his pension.

Confronted by FOX News at the time, Bertucci maintained he had done nothing wrong.

Now, it seems, the U.N. apparently doesn't think so either. Bertucci has been welcomed back by the world organization as an invited top-level expert at a high-profile conference in Seoul, South Korea, on "Building Our Humanitarian Planet."

The conference was jointly sponsored by the U.N. Department of Economic and Social Affairs (UNDESA), which includes the branch of the U.N. bureaucracy where Bertucci used to preside, and whose head was Bertucci's boss.

The conference, dubbed World Civic Forum 2009, was co-sponsored by South Korea's Kyung Hee University. It was intended as the international kickoff of a new drive by UNDESA to build support among universities and other civil institutions for the United Nations' Millennium Development Goals, which aim to cut world poverty and increase efforts at halting climate change.

Among those attending the opening ceremonies was Han Seung-soo, Prime Minister of South Korea — meaning that the conference was a very high level occurrence on U.N. Secretary General Ban's home turf. (Before taking over at the U.N., Ban served as South Korea's foreign minister.)

Bertucci's role in "Building Our Humanitarian Planet" was widely advertised in the conference program as the chairman of two workshop sessions on "Empowering Civil Society: The Role of Public Administration."

Click here to see the conference program.

The program did not mention Bertucci's new credential as a public administration expert: he is executive director of Governance Solutions International, described on one networking website as a New York-based firm involved in "non-profit organization management."

In one of the conference sessions, which a FOX News camera crew attended, Bertucci made a presentation touting locally administered forestry preservation projects in developing countries to prevent climate change.

Sitting nearby during that session was Roberto Villareal, a senior official of the Division of Public Administration and Development Management (DPADM), the office Bertucci used to head during the lengthy investigation of the Greek trust fund scandal.

Click here to see video of Bertucci at the conference.

Among those also attending the conference was Sha Zukang, the U.N.'s undersecretary general for UNDESA, who was formerly Bertucci's boss. On this occasion, he represented UNDESA as the conference's major global sponsor.

Click here to see Sha's conference role.

Sha is acutely aware of the charges against Bertucci: the report containing them lingered on his desk for weeks after an 18-month investigation by the U.N.'s watchdog Office of Internal Oversight Services, without any action on Sha's part, before being taken up by Secretary General Ban during the last days of Bertucci's official career.

Indeed, another recommendation of the report was that Sha's department repay $34,000 in wrongly awarded contracts to consultants wrongly assigned by Bertucci — just a small fraction of the funds allegedly misspent in the scandal. There is no evidence that DESA ever acted on the recommendation.

Neither U.N. Secretary General Ban's office nor the office of DESA Undersecretary General Sha responded to a lengthy list of questions from FOX News about Bertucci's presence at the conference.

Among the questions: who invited him, the role of DESA and DPADM in selecting him as an expert, and whether his role in the Greek scandal was discussed before he was invited.

Bertucci's sudden renaissance at an important conference sponsored by his former boss is only the latest mystery surrounding the last years of Bertucci's career, which included several years of stymied, delayed and sidelined investigations into the Greek project scandal, preceded by even more years of unavailing Greek government complaints about DPADM's handling of its money.

Perhaps the biggest mystery of all is the U.N. tolerance for Bertucci's failings — or at least, a deep unwillingness to act on them — even after Secretary General Ban took office on Jan. 1, 2007, after promising to hold U.N. civil servants to "the highest standards of professionalism and integrity."

By that time, Bertucci's involvement in a project known as the United Nations Thessaloniki Center (UNTC) for Public Service Professionalism had been a matter of public controversy for at least three years. Funded with Greek money, it was intended to strengthen public administration in various Balkan countries, and help to reduce corruption.

But by 2003, the Greeks were already demanding an investigation of the way the first $1.1 million of their money had been spent. Their complaints deepened during 2004 and 2005, as the Athens government insisted that it could see nothing being accomplished. U.N. auditors looked into the matter in May 2006, and discovered "indicators of irregularities," — but nothing happened.

Finally, in April, 2007, FOX News revealed that U.N. watchdogs had been appealing to Sha's predecessor as head of DESA to quit rejecting the auditors' recommendations that the U.N. assign responsibility for the situation. That official retired that year and, in effect, tossed the whole problem on to Sha.

Sha began delaying matters himself, as the investigative report on Bertucci continued to sit on his desk.

In fact, even Secretary General Ban's eventual referral of Bertucci for disciplinary action could be considered part of the stalling game. The U.N. customarily never pursues actions against employees who have left the organization, and their retirement pensions are considered sacrosanct, no matter what they have done.

Ban's tardy referral of Bertucci's case meant that he could continue to pay lip service to the notion of enforcing high ethical standards, without having to do anything significant about it, at least in Bertucci's case.

All of which raises the intriguing question: what is so special about Guido Bertucci that his tarnished presence continues to be welcome, even at the highest levels of the U.N., and even on the Secretary General's home turf?

It is a question those high level officials are so far not answering.

George Russell is executive editor of FOX News.