The credibility of FIFA, soccer’s international governing body, took another severe hit Wednesday when the organization’s chief ethics investigator resigned in protest over the smothering of his report about corruption in the much-criticized bid process for the 2018 and 2022 World Cups.

In his resignation statement, Michael J. Garcia, a former United States attorney for the Southern District of New York, strongly suggested that scandal-plagued FIFA was incapable of reforming itself from within.

“No independent governance committee, investigator or arbitration panel can change the culture of an organization,” Mr. Garcia wrote.

A spokeswoman said Mr. Garcia was not immediately available for interviews.

In his statement, in an unnamed but pointed reference to Sepp Blatter, FIFA’s beleaguered president, Mr. Garcia cited a “lack of leadership” within FIFA to become more transparent and ethical in its behavior in the face of widespread international ridicule.