Blatter’s office was searched today (25 September) and data seized, according to a statement from the Office of the Attorney General of Switzerland (OAG), which is investigating corruption at FIFA.
The statement said criminal proceedings had begun against Blatter in relation to suspicions that he signed a contract with the Caribbean Football Union in 2005 that was "unfavourable to FIFA". There are suspicions that Blatter "violated his fiduciary duties and acted against the interest" of FIFA in relation to how the deal was implemented.
Blatter is also suspected of making a "disloyal payment" to UEFA present Michel Platini in 2011 "at the expense of FIFA".
The OAG said its officials "interrogated" Blatter today (25 September) following a meeting of the FIFA Executive Committee, and Platini was "asked to provide information".
"Furthermore, the OAG conducted on 25 September 2015 a house search at FIFA headquarters with the support of the Federal Criminal Police. The office of the FIFA President has been searched and data seized."
FIFA released a statement this afternoon, publicised on its official Twitter account, saying the organisation has been "co-operating" with the OAG and "complied with all requests for documents". It added: "We will continue this level of co-operation throughout the investigation."
FIFA’s statement added that the group "facilitated" the interviews at its HQ as part of its "ongoing co-operation".
FIFA Statement on the Office of the Swiss Attorney General Investigation. pic.twitter.com/NX9reVosp3— FIFA Media (@fifamedia) September 25, 2015
The criminal proceedings against Blatter are the latest in a line of crises at FIFA in recent months. It follows a series of arrests and allegations of corruption among high-profile individuals at the organisation in the summer, along with confusion about whether Blatter would be stepping down.
In July Walter De Gregorio, comms and public affairs director at FIFA, stepped down days after making a joke on Swiss TV at the expense of Blatter. It later emerged that FIFA hired US-based Teneo Holdings for "operational and reputational" work.
Separately, former London 2012 Olympics and Paralympics comms and public affairs chief Jackie Brock-Doyle has predicted FIFA could cease to exist in five years unless it integrates itself better with others in the football world.
The current chairman of PR agency Good Relations was not making reference to today’s news about criminal proceedings against Blatter.
Speaking at the PRCA conference in London this morning, she contrasted FIFA’s situation with the way stakeholders were brought together to make the 2012 Olympics a success.
Brock-Doyle said: "Right now [FIFA] could not be trusted less. But football fans couldn’t care less either.
"There’s a total disconnect with the sport we watch week in, week out, and the governing body currently under investigation; more than a disconnect, a severance.
"There’s no integration between FIFA and the matches we watch. Does that matter? I think it does and I think the question for FIFA will be its relevance to the world in the future."
She said football clubs "have way more power than the international governing body, so FIFA could become irrelevant or cease to exist".
"That could be the fall-out from lack of integration and a total breakdown in trust at the top level.
"Does anyone really care if FIFA survives? Perhaps some, but unless it integrates better with the properties it has, the clubs that carry out the games, it will cease to exist and time will tell whether that happens. I give it five years."