In the voicemails, Favre is heard inviting Sterger to his hotel. Favre has admitted to leaving the voicemails but not to sending inappropriate pictures of himself.
The NFL concluded its investigation Dec. 29, 2010 by fining Favre $50,000. The fine drew the ire of some critics who said the punishment wasn't harsh enough. Favre reportedly makes $50,000 in just five minutes of game time. His base salary is $11.6 million.
The league said that Commissioner Roger Goodell "could not conclude" that Favre violated the NFL's personal conduct policy given the evidence available to him.
Officials from the league said that forensic evidence gathered during the nearly three-month investigation did not establish that Favre sent the objectionable photographs to Sterger.
"This has been a messy story from the get-go ... and it's a messy ending to the story. I don't know if anybody is happy with it except maybe Brett Favre, who has gotten away ... with a slap on the wrist," ABC News sports contributor Christine Brennan said on "Good Morning America" when the fine was announced.
The fine was intended to reprimand Favre for not being "candid in several respects during the investigation, resulting in a longer review and additional negative public attention," the league said.
"Brett Favre not cooperating, that's significant, that's not just a little laugh-it-off kind of thing," Brennan said. "Why didn't Roger Goodell, who is a get-tough commissioner, why didn't he suspend Brett Favre for the presumably final game of his career [and] send a big statement to NFL players that this is unacceptable?"
The NFL said it had reviewed media reports that Favre had made passes at two massage therapists who worked for the New York Jets, but that "people with relevant information" refused to be interviewed. It appears those people have now come forward with the lawsuit.
The Jets as a team have also been in hot water for allegedly cat calling Ines Sainz, a Mexican sideline reporter for TV Azteca, in September of 2010.
Sainz called the Jets' locker room an "uncomfortable" environment for a woman.
Meanwhile, Favre, who was sidelined by injury in the Minnesota Vikings' final game of the season on Sunday, said that he is retiring from the field for good. He's retired twice before but then come back to the game.