EDEN PRAIRIE, Minn. — Down to the last few days of the season and maybe Brett Favre’s career, the NFL ended a slow-paced investigation of tawdry allegations against the quarterback with a $50,000 fine and a rebuke for not being candid.

The league punished one of its marquee players for failing to cooperate with investigators who were trying to determine if the 41-year-old quarterback sent inappropriate messages and below-the-belt photos to Jenn Sterger in 2008, when both worked for the New York Jets.

The ruling came days before what could be the final game for the three-time MVP. He’ll start for Minnesota at Detroit on Sunday if he’s recovered from a concussion sustained Dec. 20 against Chicago, and has said this will be his final season, though he’s unretired in the past. He made the declaration even before his NFL record for consecutive starts was snapped at 297 in mid-December.

It’s been a tough season on the field for Favre and his Vikings, and by the league’s own admission, the investigation begun in early October has generated plenty of bad publicity for all the parties involved — Favre, Sterger and the NFL itself.

Yet Commissioner Roger Goodell "could not conclude" that Favre violated the league’s personal conduct policy based on the evidence currently available to him, the league said in a statement announcing the fine.

Forensic analysis failed to establish that Favre sent the objectionable photographs to Sterger, the league said.

Favre’s punishment stems from Goodell’s determination that he was "not candid in several respects during the investigation resulting in a longer review and additional negative public attention for Favre, Sterger and the NFL," the league said. The commissioner also told Favre that if he had found a violation of the league’s workplace conduct policies, he would have imposed a "substantially higher level of discipline."

The NFL said its sole focus was on whether Favre violated workplace conduct policy, not to "make judgments about the appropriateness of personal relationships."

There was no comment from Favre and his agent, Bus Cook, did not return messages.

The ruling drew a swift and bitter response from Sterger’s attorney, who accused the league of favoritism.

"It clearly shows that an NFL star player was given preferential treatment and tells all other players that failure to cooperate may cost you some money but will not result in other punishment," said Joseph Conway, who added there was "ample evidence" the photos were of Favre.

"Additionally, today’s decision is an affront to all females and shows once again that, despite tough talk, the NFL remains the good old boys’ league," Conway said.

Conway said Sterger is undecided about whether to take legal action against Favre, the Jets or the NFL.

The league said its investigation dragged out because of difficulties in setting up interviews with "certain key individuals," the complication of retrieving and reviewing electronic records and Goodell’s decision to meet with both Favre and Sterger before reaching a conclusion.

Vikings players had Wednesday off, and interim coach Leslie Frazier said he "never put a lot of energy or focus" on the situation.

"I can’t really speak for Brett and how it has affected him on and off the field," Frazier said. "I just know that whenever he’s in meetings, whenever he’s on the practice field, he’s been all in in every situation. I’ve never thought for a moment that he wasn’t as prepared as well as he’s prepared ever."

Frazier said the organization is "extremely supportive of the league office," but the coach also said he was "pulling for Brett and his family."

Goodell in a memo sent Wednesday to all NFL teams said that "every member of every club’s staff should be able to work in an environment free of harassment or hostility, and one in which every employee is valued, respected, and given a full opportunity to contribute to the goals of the club and the NFL."

Favre’s fine will help fund a new training program on workplace conduct around the league, though for the multimillionaire QB the penalty is a pittance. Even while sitting out of Tuesday’s game at Philadelphia because of post-concussion symptoms, Favre essentially earned $50,000 over about five minutes of action.

According to NFLPA data, Favre’s base salary for this season is $11.6 million.

The allegations against the quarterback surfaced on the website Deadspin, which posted a video Oct. 7 that included text messages and voicemails allegedly left by Favre for Sterger, including one in which he invites her to his hotel.

A former model who was a Jets gameday hostess and later appeared on the Versus television network, Sterger refused to speak on the record to the website. Weeks after the story broke, she talked with league investigators and cooperated fully, according to her manager Phil Reese.

Deadspin editor in chief A.J. Daulerio acknowledged paying a third party for the material it posted on Favre and said that he could not guarantee the material was genuine.

The league also reviewed media reports that Favre pursued two massage therapists who worked at the Jets’ facility in 2008. But the NFL said that claim could not be substantiated because people with "potentially relevant information" declined to be interviewed or cooperate with investigators.

According to the league, its investigation included the following: "an analysis of publicly available reports; a series of interviews with knowledgeable individuals, including Sterger and Favre; a review of communications between the two furnished to our office; and independent forensic analysis of electronically stored material."

The investigation was also limited in several respects because the matter was not brought to its attention until two years after it allegedly occurred, the league said.

Favre has consistently refused to answer reporters’ questions about the allegations. He said early on that he had enough to worry about with the Vikings’ next opponent, and that’s certainly been true this season.

Convinced to come back for one more run at a title by three Minnesota teammates who flew down to see him in Mississippi, Favre’s second year with the Vikings has been nothing like the charmed run of last season, which ended with a heartbreaking loss to New Orleans in the NFC championship game.

With 11 touchdowns and 19 interceptions, Favre’s passer rating of 69.9 ranks ahead of only Arizona’s Derek Anderson and rookie Jimmy Clausen of Carolina.

Favre also has been battered by injuries to his ankle, chin, ribs, back, head and throwing shoulder — the one that forced him to finally miss a start, against the Giants on Dec. 13. But despite all his troubles, Favre has said all along that he did not regret coming back for a 20th NFL season.

"If you had seasons like you did last year, every year," he said recently, "I don’t think you would appreciate them nearly as much."