U.S. prosecutors on Monday made public their 2013 plea agreement with Chuck Blazer, revealing that the former FIFA executive committee member had been secretly providing authorities information for nearly two years before he admitted guilt.

Prosecutors made the agreement with the key cooperating witness public after a federal judge in Brooklyn, New York, on Thursday ordered it unsealed at the request of media outlets following the indictment of 14 FIFA officials and corporate executives.

The document revealed that Blazer, the former general secretary of CONCACAF, soccer's governing body in North and Central America and the Caribbean, began providing prosecutors information as early as December 2011.

The Justice Department had originally opposed making the agreement public. But U.S. District Judge Raymond Dearie said prosecutors had failed to meet their "high burden" to establish the document should remain sealed.

A spokeswoman for the Brooklyn U.S. Attorney's office declined comment. Blazer's lawyer did not immediately respond to a request for comment.

Blazer, 70, is one of four individuals who had secretly pleaded guilty in the years before the case was announced on May 27.

He has become a key cooperating witness in the probe, which has engulfed FIFA and led the governing body's president Sepp Blatter to announce his resignation.

Blazer, who had been a FIFA executive committee member from 1997 to 2013, secretly pleaded guilty in November 2013 to 10 counts including conspiracies to commit racketeering, wire fraud and money laundering.

According to a redacted transcript of his plea hearing, Blazer admitted that he and other officials took bribes in connection with the 1998 and 2010 World Cups.

Blazer also admitted to with others accepting bribes and kickbacks related to five different editions of CONCACAF's premier event, the Gold Cup, between 1996 and 2003.

He also admitted to committing tax evasion and to working with others to transfer the money between accounts in an effort to conceal the kickback schemes.