Update- January 21, 2014
An NFL investigation reportedly has determined that 11 of the 12 game footballs used by the New England Patriots during Sunday's AFC Championship game were under-inflated by two pounds per square inch below the required minimum.
In an NFL letter about the investigation that was shared with the Boston Globe, the Patriots were informed that initial findings indicated their game balls did not meet requirements, the newspaper reports.
ESPN reported late Tuesday that the league had made the determination earlier in the day and described NFL officials as "disappointed", "angry", and "distraught." However, it is not known how the balls became under-inflated.
Under NFL rules, each team is provided with 12 balls to use on offense during the game. The balls are required to made available for inspection and approval by the game referee two hours and fifteen minutes before kickoff. The balls are required to be inflated between 12.5 and 13.5 pounds per square inch and weigh between 14 and 15 ounces. Teams are not allowed to alter the balls in any way once they are approved by the officiating crew.
The Boston Globe reported late Tuesday that the officiating crew for Sunday's game, led by referee Walt Anderson, discovered at halftime that the game balls were under-inflated after testing them with two different gauges.
Earlier Tuesday NFL senior executive vice president for football operations Troy Vincent told ProFootballTalk that the league expected to complete its investigation in "the next two or three days." The league did not comment publicly when reached by Fox News Wednesday morning.
The Patriots defeated the Colts 45-7 to advance to their sixth Super Bowl since 2001. They will play the Seattle Seahawks in the Super Bowl on Feb. 1 in Glendale, Ariz.
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NFL spokesman Brian McCarthy confirmed the probe Monday, following the AFC championship game, in which the Patriots demolished the Indianapolis Colts, 45-7. The charge was first made Sunday night, when an Indianapolis reporter that the NFL had seized at least one game ball from the AFC championship game to examine whether pigskins were intentionally deflated to make them easier to throw and catch.
"The NFL is investigating the possibility," Bob Kravitz, of WTHR, tweeted, adding that, "at one point the officials took a ball out of play and weighed it."
If the Patriots did cheat, it would not be the first time. The team was penalized a first-round draft pick, fined $250,000 and head coach Belichick was personally fined $500,000 after an investigation by the NFL determined the team had illegally videotaped their opponents hand signals during a 2007 game.
And unsubstantiated accusations of cheating have long dogged the team, stemming from their Super Bowl wins in 2002, 2004 and 2005. The St. Louis Rams claimed the team illegally videotaped their walk-through practices prior to the 2002 game, and players on the other defeated opponents have said the Patriots seemed to have inside knowledge of their playbooks.
The Patriots lost the Super Bowl in 2008 and 2012, both times to the New York Giants.
Deflating footballs would theoretically have made it easier for Brady, who completed 23 of 35 passes for 226 yards and three touchdowns, to throw and for his receivers to catch in the bad weather of Sunday's game in Foxboro. But it also should have benefited Colts' quarterback Andrew Luck, who had a miserable game, completing 12 of 33 passes for a mere 126 yards.
According to NFL rules, home teams are required to provide 36 balls for outdoor games and make the balls available for testing with a pressure gauge prior to the game.
The Patriots were also accused of flouting the rules in the game before Sunday's contest, in which they beat the Baltimore Ravens using unorthodox formations that Ravens Coach John Harbaugh said were designed to confuse the officials and his defense.
However, the margin of victory and the fact that the Colts used the same game balls make it unlikely the cheating, if it occurred, had much of an impact on the game's outcome. If the allegation is proven, the NFL could take away draft picks from the Partriots.
The University of Southern California, under Lane Kiffin, was fined for deflating footballs in 2012 against arch-rival Oregon. Kiffin blamed a student-manager, who was fired.
Super Bowl XLIX takes place Feb. 1 in Glendale, Arizona. The defending champion Seattle Seahawks, who punched a return ticket with a 28-22 win over the Green Bay Packers prior to the Patriots-Colts game, are a two-and-a-half-point favorite in early betting.