"They feel like Favre had something (in place), and that's why he was so anxious to get his release all of a sudden," the person said.
The tampering charges were first reported by Foxsports.com earlier Wednesday.
The person said the league already has reviewed evidence provided by the Packers, and team officials believe a league examination of telephone records would indicate more than "normal contact" between Favre and Vikings offensive coordinator Darrell Bevell, a former Green Bay assistant. According to the person, Packers officials also believe the contact began before Favre and his agent, Bus Cook, formally asked the Packers to release him.
NFL spokesman Greg Aiello said the league had no comment on the report. Cook did not return a telephone message left by The Associated Press earlier Wednesday.
The tampering charges added a new twist to the Favre saga, which seemed to be over when Favre retired in early March but now has been sizzling for several weeks.
Now, with Favre potentially headed back to an even chillier reception than the below-zero conditions in his last game at Lambeau Field when he makes a scheduled appearance at the Packers' Hall of Fame banquet this weekend, the next step in the iconic quarterback's plan to maneuver his way out of Green Bay is unclear.
Cook told ESPN on Wednesday that he and Favre have "no definite plans to ask for reinstatement" and it was up to the Packers to decide what to do next.
"It's their move," Cook said.
Favre was in Los Angeles for Wednesday night's taping of the ESPY Awards. Host Justin Timberlake zeroed in on Favre sitting in the audience with his wife, Deanna.
"What have you been up to lately? I haven't seen you anywhere," Timberlake said. "Just chillin'? Yeah, me too."
That's just the first of several awkward moments potentially on tap for Favre this week.
Should Favre keep his commitment, his return to Lambeau will come a little more than a week after formally requesting to be released - and only days after expressing his distrust of Packers management, insisting in an interview with Fox News on Monday that the team pressured him into making his retirement decision.
Favre could see some of the same folks he criticized in his trip back to Lambeau. He also might run into Packers offensive line coach James Campen, a former teammate who was dragged into the middle of the controversy this week.
In an unaired portion of Favre's interview with "On the Record With Greta Van Susteren," Favre apparently said Campen recently made an unexpected visit to his home in Mississippi and said he had "an answer" for Favre regarding his desire to unretire.
"He says, 'You know, I know they told you they're moving on and playing there's not an option,"' Favre said, according to a full transcript of the interview obtained by the Milwaukee Journal Sentinel. "Playing here in Green Bay is not an option, which that's what they want. They want to move on. But I'm telling you, if you reinstate or you force their hand, back them in a corner, they feel like they have no other option, they're going to accept you back."'
"And he said, 'Just telling you.' And I said, 'OK."'
McCarthy said the Packers told Campen to visit Favre as a friend, not on behalf of the team, once they heard Favre was having second thoughts about retirement earlier in the offseason. McCarthy said it was Favre and his representatives, not the team, who turned Campen into an "intermediary" between Favre and the front office.
"I think he's totally, wrongly been illustrated in this," McCarthy said. "Ted (Thompson, Packers general manager) would not even talk to Campen about this. He said, 'Hey, your personal relationship with Brett Favre is bigger than this, so don't ever put yourself in that position.' ... James was put in a tough spot. He was put in a situation that was purely personal."
A movement to rally fan support for Favre has fizzled so far. A rally in Green Bay drew fewer than 200 fans Sunday, and Monday's rally in the Milwaukee suburbs drew only 30 despite widespread local media attention. But shareholders supporting Favre could call attention to the issue.
AP Football Writer Dave Goldberg in New York and AP Sports Writer Beth Harris in Los Angeles contributed to this report.