Investigators have carried out further house searches as part of a widening probe into bribery allegations over the awarding of the 2006 World Cup to Germany, Swiss prosecutors say.
The inquiry is centred on the 2006 World Cup organising committee which includes former Germany captain Franz Beckenbauer, who has denied corruption.
It has now been broadened to include former senior Fifa official Urs Linsi.
German media reports say that a slush fund was set up to buy Fifa votes.
The inquiry centres on four people – including Mr Beckenbauer – who were part of the German bid.
Investigators have been especially concerned about a payment of about 10m Swiss Francs ($9.8m; £7.9m) to Fifa in 2005.
“The Office of the Attorney General (OAG) of Switzerland confirms that on 23 November 2016 it conducted house searches with the support of the Federal Office of Police [fedpol] at various locations in the German-speaking part of Switzerland,” the OAG said in a statement.
The OAG began its investigation last year into allegations that four members of the 2006 World Cup organising committee were involved in fraud and money laundering.
On Wednesday prosecutors announced they were also investigating Mr Linsi, who served as Fifa’s secretary general between 2002 and 2007.
The case first made the headlines in October 2015, when German news magazine Der Spiegel accused Germany of using the secret slush fund to buy Fifa votes in support of its bid to host the 2006 World Cup.
The money allegedly came from the late Robert Louis-Dreyfus, who in 2000 was head of German sportswear giant Adidas. It was allegedly provided at the request of Mr Beckenbauer, who led the committee seeking to secure Germany’s right to host the event.
Mr Beckenbauer previously admitted to making errors in relation to the bid but has denied deliberate wrongdoing.
A separate report into alleged irregularities over awarding the World Cup to Germany in 2006 was published in March by the German Football Association.
It said that while there was no evidence of Germany paying Fifa members in return for votes, payments were made to at least one former Fifa official through a complicated network of bank accounts.