Switzerland named a special prosecutor to review criminal complaints against FIFA chief Gianni Infantino and Attorney General Michael Lauber after the men held undocumented meetings while Lauber's office was investigating suspected graft surrounding the global soccer body.
Lauber last month became the subject of an impeachment process relating to his handling of the soccer inquiry.
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The watchdog overseeing Swiss federal prosecutors -- Lauber's office -- placed him under investigation last year after he held three closed-door meetings with FIFA President Infantino regarding the status of the corruption inquiry.
Lauber and Infantino both previously denied any wrongdoing.
On Friday, the watchdog announced that lawmakers conducting the impeachment process had asked it to review Infantino's conduct too in the investigation after three criminal complaints were filed against both men and other unnamed persons with prosecutors in the capital Bern.
Stefan Keller, a presiding judge at a Swiss cantonal court, had been appointed as "extraordinary prosecutor" on June 29 to review the complaints and determine whether criminal charges should be brought against Lauber.
FIFA said it welcomed the appointment and was cooperating fully. Previous complaints against Infantino had been dismissed by various authorities, it said.
"There was a mountain of questions," Infantino said in a statement provided by FIFA, referring to the investigations in which world soccer was involved at the time of the meetings.
"So it's legitimate to offer to contribute to the Swiss Attorney General about the clarification of these events, hoping that those who have done criminal acts and damaged FIFA will be held to account for that," he said.
Lauber's office said it had taken note of the special prosecutor's appointment, declining further comment.
A Swiss court last year ordered Lauber to recuse himself from world soccer investigations, ruling that his meetings with Infantino raised the appearance of bias. Other federal prosecutors are now running the investigations.
The investigations against Swiss-based FIFA involve allegations of breach of trust, fraud, embezzlement and money laundering. Lauber's office is conducting around 25 criminal investigations alongside 15 foreign law enforcement agencies.
A fourth criminal complaint has been filed, the watchdog said. No details of the complaints have been released.