Whistleblower Chuck Blazer has denied an American conspiracy is behind the investigation into the bribery scandal surrounding Mohamed Bin Hammam's bid to become Fifa president.
Bin Hammam, Fifa vice-president Jack Warner and two Caribbean Football Union (CFU) officials have been suspended pending the outcome of the probe by Fifa's ethics committee.
As part of the probe, private investigators hired by the ethics committee began to interview the heads of Caribbean federations at the centre of the scandal on Tuesday.
However, it appears as many as 18 of the 25 associations have refused to attend the summons to Miami, Florida.
One association has also complained to Fifa that the investigation is "biased" towards the USA - one of the defeated bids for the 2022 World Cup - and has called for ex-FBI director Louis Freeh to be replaced as lead investigator.
But Blazer, the USA's Fifa member who first brought the allegations to the attention of the world governing body, denied a conspiracy.
He said: "To say there is an American conspiracy is nonsense. The only things that were American in this were the 100 dollar bills.
"I am nothing to do with the investigation. If national associations do not respond to Fifa's summons that's up to Fifa to deal with it."
The probe is looking into claims the 25 members of the Caribbean Football Union were each paid US$40,000 (in four packs of 100-dollar bills each totalling 10,000 dollars) to vote for Bin Hammam as Fifa president.
Fifa's ethics committee have summoned all 25 associations to the interviews in Miami to be questioned about claims they were given the money as a bribe by Bin Hammam and Warner at a meeting in Trinidad on May 10 and 11.
But the letter of complaint to Fifa president Sepp Blatter by a Caribbean federation chairman says: "The investigation is tainted and biased and clearly has a US-driven agenda.
"I write to expose what can now be confirmed as attempts at intimidation and terrorisation by forces who wish to divide and destroy the 30-year history of the CFU."
The letter asks Blatter to replace Freeh with a "truly independent investigator and secure a neutral venue for the interview of any Caribbean Football Union member other than the USA".
It also points out former USA president Bill Clinton worked on the USA 2022 bid, during the time Freeh was FBI director, and the main complainants, Blazer and Chicago-based lawyer John Collins, are American, as are the investigators with the "interrogation being conducted on American soil".
The connection between Freeh and Clinton may be tenuous however as they had a well-publicised feud during almost all the time the former president was in the White House.
A letter from Fifa's ethics committee to the associations has told federation chiefs to meet investigators from June 7-9.
It states: "Although you are under no obligation to attend such a meeting please be advised that the FIFA ethics committee may draw a negative inference in the event that you (i) do not make the arrangements sought herein, or (ii) do not attend the meeting requested.
"Furthermore we kindly remind you that as an official you have a duty of disclosure and reporting, including providing any evidence requested for inspection."
Fifa say they will pick up the tab for travel to and accommodation in Miami and say if officials cannot make the dates requested they must offer an alternative to take place within the next 10 days.