Fifa started the biggest disciplinary investigation in its history on Monday into the violence at the end of the Turkey-Switzerland World Cup play-off.
The second leg in Istanbul ended in chaos after the Swiss qualified for the finals on the away goals rule.
"In terms of scope it is the most voluminous disciplinary investigation in our history," said a spokesman for world football's governing body.
President Sepp Blatter has promised the inquiry will finish before 9 December.
That is when the draw for the finals in Germany next summer takes place in Leipzig.
The spokesman added that the investigation would include interviewing several of the players and officials from both countries involved in the fracas at the end of the game.
"We have begun the enquiry in Zurich today which will involve interviewing more than 20 people," he said.
"These include the two national coaches, players, officials and technical staff from both countries.
"Because of the scale of the inquiry and the possible sanctions we have to ensure that legally everything is done exactly right."
The match in Istanbul ended with tempers fraying and television footage showed Switzerland's Benjamin Huggel kicking a member of the Turkish coaching staff as he ran off the pitch.
The Swiss players left the pitch under a hail of objects thrown by the Turkish crowd and defender Stephane Grichting was taken to hospital with a groin injury following trouble in the tunnel.
The trouble in Istanbul took the shine off Switzerland's qualification for next year's World Cup.
Kobi Kuhn's team lost 4-2 to Turkey after a 2-0 victory in the first leg but won the tie on away goals.
Tuncay Sanli scored a hat-trick for the Turks, who finished third in the 2002 World Cup, but Marco Streller's 84th-minute goal put the Swiss through.