FIFA's chief investigator Michael Garcia is expected to interview all the remaining members of the executive committee who took part in the controversial vote for the 2018 and 2022 World Cups.
Only 11 of the 24 members - plus FIFA president Sepp Blatter - who took part in the vote in December 2010 are still on the committee, with the others having either retired or, in some cases, been banned or resigned while under investigation.
Last September, Garcia said his probe into the bidding process for the 2018 and 2022 World Cups would see investigators interview representatives of every bid team - interviews have already taken place with a number of officials who worked on England's unsuccessful 2018 bid.
Sources connected to the world governing body say Garcia is now expected to interview those 12 executive committee members who are still in office.
It is expected the interviews will focus on the bidding process and look into any allegations of wrongdoing and breach of bidding rules including collusion between bids.
It comes after a report that the FBI is investigating payments from a company owned by Qatari Mohamed Bin Hammam to fellow former FIFA member Jack Warner and his family.
Both men left FIFA in disgrace following a 2011 corruption scandal.
Meanwhile, the former head of Australia's unsuccessful bid for the 2022 tournament said he hoped the investigation would come up with "the right answers".
Frank Lowy said he still hoped FIFA would refund the £25million public money spent on the Australian bid if FIFA moves the 2022 World Cup in Qatar to the winter.
Lowy told Australian media: "It is generally known ... that the process was not exactly a good one, to say the least.
"I've read the papers and while I would not use the word 'corruption', I think the process wasn't quite clear to everybody and the jury is still out.
"It was not a level playing field and I said at the time that we had not heard the last word about the process.
"I still don't think it is going to go away. These stories are coming up from time to time and until FIFA makes the final decision it will regurgitate each time."
In terms of a winter World Cup, Lowy added: "I feel if FIFA changes the date, then I think they hope to refund the people that bid on a certain time [in the summer]
"Whether we get the money back or not is hard to say, but I [would] certainly put the claim in."
Qatar's 2022 World Cup organising committee said its bid committee strictly adhered to FIFA's bidding regulations.