Fifa president Sepp Blatter spent much of Friday underground. Starting at 9am, Blatter and a few dozen other top executives were ensconced in an isolated conference room three levels below ground at Fifa's headquarters here in Zurich, discussing pressing issues like budgets, governance reforms and the scheduling of future World Cup tournaments. All seemed normal and routine.

When Blatter surfaced in the early afternoon, however, he was stunned to find a group of officials from Switzerland’s office of the attorney general waiting for him. Over the next few hours, the officials interrogated Blatter at length. They searched his office, situated five floors above the bunker, on the top floor of Fifa House, and took boxes of documents, then informed Blatter that he was under criminal investigation.

The investigation centres on “suspicion of criminal mismanagement and suspicion of misappropriation” of funds, according to a statement released by the Swiss authorities, and it has now connected world soccer’s top official directly to a corruption scandal at the highest level of the sport.

Swiss officials said on Friday that they were looking specifically into Blatter's suspected approval of a curiously small contract for World Cup television rights and a surprisingly large payment to Uefa president Michel Platini, a leading candidate to succeed Blatter as Fifa president next year.

Under Swiss statutes, both criminal mismanagement and misappropriation can be punishable by jail time.

A lawyer for Blatter, Richard Cullen, said that a review of documents would show that “certainly no mismanagement occurred”.

“Mr Blatter is co-operating and we’re confident that when the Swiss authorities have a chance to review the documents and the evidence they will see that the contract was properly prepared and negotiated by the appropriate staff members of Fifa who were routinely responsible for such contracts,” Cullen said.

Blatter had planned to take part in a news conference Friday afternoon to discuss the just-concluded meeting of Fifa’s executive committee – the session that took place in the bunker. That news conference was first delayed and then cancelled, however, as Swiss investigators spent much of the afternoon interviewing Blatter in what was described as a mostly cordial conversation.

This is the second time that Swiss authorities are known to have searched and seized data at Fifa’s headquarters. The first came on May 27th, when 14 top soccer and marketing officials were arrested in Zurich as they gathered for Fifa’s annual congress. The United States Department of Justice had issued those arrest warrants, many of which were carried out by the Swiss police at a luxury hotel in the early morning hours. Blatter was not implicated or charged that day, but Swiss and American officials later said that he was a target of their investigators.

Now, four months later, the Swiss authorities are directly investigating Blatter, who has led Fifa since 1998. His tenure has seen significant growth of the game and the organisation’s coffers, but also a variety of corruption scandals.

A United States law enforcement official said Friday’s announcement by the Swiss authorities was independent of the Justice Department’s investigation, which continues. But Swiss and American investigators continue to co-ordinate their efforts, and the teams met just last week.

One part of the case announced Friday involves a contract Blatter is said to have signed that assigned valuable World Cup television rights to the control of an indicted former Fifa official, Jack Warner, for far below market value. Blatter is accused of violating his fiduciary duty to Fifa in his role as president by signing the contract in 2005, which the Swiss authorities called "unfavourable to Fifa."

The contract, obtained by the Swiss broadcaster SRF, which posted excerpts on its website, awarded the Caribbean Football Union, which Mr. Warner controlled, the rights to the 2010 and 2014 World Cups for a total of $600,000. Warner, in turn, licensed those rights for roughly 33 times that amount, or $20 million.

The Swiss authorities also said Blatter was suspected of making a “disloyal payment” of two million Swiss francs (€1.665 million) to Platini. The payment, they said, was for work performed between January 1999 and June 2002 but was not made until February 2011, or roughly three months before Blatter won a fourth term as Fifa president.

Platini released a statement that said the payment was proper for work he had performed, though he did not explain the nearly decade-long delay in receiving it.

“Regarding the payment that was made to me, I wish to state that this amount relates to work which I carried out under a contract with Fifa, and I was pleased to have been able to clarify all matters relating to this with the authorities,” Mr. Platini said.

In addition to the potential for criminal charges against Blatter, the revelation of Platini’s potential involvement could have a significant impact on the special election for next Fifa president.

People close to Blatter said he was shocked to be questioned by Swiss investigators Friday; in fact, in recent days, he had even hinted that he might be considering trying to extend his term as president. Multiple officials here for meetings this week said . Blatter told Fifa staff members that he would be president “at least” until February, implying that it was possible he would reverse his decision to stand down.

That now seems unlikely. It is also possible Blatter could be the subject of an investigation by Fifa’s independent ethics committee. Blatter’s top deputy, Jérôme Valcke, was suspended by the ethics committee last week from his role as Fifa’s general secretary amid allegations he was involved in a scheme to sell World Cup tickets for personal profit. Valcke has denied involvement.

Andreas Bantel, a spokesman for the ethics committee, said that if there is enough evidence to warrant an investigation, then “the investigatory chamber will start a formal proceeding against anybody, regardless of his name.”

In the meantime, Blatter is expected to remain in Switzerland. Once a globe-trotting ambassador for soccer, he has limited his travel since the arrests in May, only visiting countries that do not have extradition agreements with the United States. For example, one decision the Fifa executive committee took this week was to relocate its next scheduled meeting, set for December in Japan, to Zurich.

(New York Times service)