The FBI and U.S. prosecutors were investigating Sepp Blatter, the FIFA president who announced his resignation on Tuesday, as part of the probe that led to last week's stunning indictments, sources familiar with the case told ABC News.
The FBI declined to comment because Blatter has not been publicly identified as a target of the investigation.
U.S. authorities last week indicted 14 people -- nine football officials and five sports-marketing executives -- who face charges of wire fraud, racketeering and money laundering. They are accused of accepting more than $150 million in bribes.
ABC News reported that the investigation hoped to use those indicted to provide information that could lead to charges against their superiors -- much as federal agents would in a mob racketeering case.
"Now that people are going to want to save themselves, there's probably a race to see who will flip on [Blatter] first," one of the sources said, explaining how the feds typically try to get people to inform on their superiors.
"We may not be able to collapse the whole organisation, but maybe you don't need to," one of the sources said.
Last month, E:60's Jeremy Schaap reported that ESPN could find no record of Blatter having entered the U.S. since 2011. Sources told Schaap that Blatter decided, because of the FBI investigation, that it would be unwise to set foot on American soil.
During last week's announcement, officials repeatedly told reporters that the investigation was ongoing.
Though that is standard language for the FBI and federal prosecutors, the sources told ABC that, in this case, it was particularly true.