The NFL had members of its security department at Winter Park on Tuesday to interview Vikings officials regarding the tampering charges the Green Bay Packers filed against Minnesota for "inappropriate dialogue" with quarterback Brett Favre, according to people with knowledge of the situation.

While the sources did not know exactly with whom NFL officials spoke, it's believed that Vikings coach Brad Childress and offensive coordinator Darrell Bevell were questioned. The fact the Vikings were asked for their side of the story a day before the team was to report to training camp and less than two weeks after the Packers filed the charges could be an indication the league is hoping to resolve the issue quickly.

It marked the latest twist in the Favre-Packers summer soap opera that now involves Green Bay's NFL neighbors to the west. ESPN reported Tuesday night that Favre -- who retired in March, then decided he wanted to unretire -- "clearly prefers to play for the Vikings."

Favre's desire to end up in purple has been speculated on previously but remains an enormous long shot, as the Packers have told Favre they won't grant him his wish to be released.

That's in part because the Packers don't want Favre signing with an NFC North rival such as the Vikings or Chicago Bears. Favre remains the property of the Packers until his contract expires after the 2010 season.

The NFL's trip to Minnesota came on the same day the Milwaukee Journal Sentinel reported that a source said Favre continued to use a Packers-issued cell phone after his retirement and that when the team checked the phone records, there were "repeated calls to coach Brad Childress and offensive coordinator Darrell Bevell."

Favre's odd decision to use a phone on which the Packers could review all calls had been speculated on last week after the Associated Press reported that Green Bay informed the NFL it felt "an investigation of the phone records would show more than 'normal contact' between the Vikings and Favre, even before he formally asked for his release to play for another team."

Bevell and Favre became friends when the former served on the Packers coaching staff from 2000 to 2005, and they have continued to stay in touch.

That made it difficult to believe the Packers could prove much by simply pointing to conversations between Bevell and Favre. If Favre's phone records provide evidence of multiple calls to Childress, it's a different story. Favre asked for his release this summer when the Packers told him Aaron Rodgers is their starter.

The Vikings are believed to be Favre's top choice for a landing spot, in part because they run a version of the West Coast offense with which he is familiar. Childress has stated publicly that Tarvaris Jackson is his starting quarterback, but the opportunity to plug in a veteran like Favre could be tempting.

The Vikings, if found guilty, could face penalties that include the loss of draft picks and fines.

While the Packers won't release Favre, the NFL Network reported Tuesday that the team has talked to multiple clubs about what it would be willing to offer in a trade and that calls have been made to franchises in both conferences.

ESPN reported later Tuesday that sources from the NFL and its players union said Packers General Manager Ted Thompson started making calls to other teams "after being encouraged by NFL Commissioner Roger Goodell to resolve the controversy surrounding Favre before they begin training camp Sunday."

The Vikings have remained quiet on the tampering charge since news broke last week. Owner Zygi Wilf told the Star Tribune last week that he wouldn't comment on the Packers' accusation but added, "Let's put it this way, I look forward to the opening game in Green Bay." The Vikings will face the Packers in the season opener Sept. 8 at Green Bay.