With the NFL investigating an accusation that the Patriots used underinflated footballs in the AFC Championship Game last week, coach Bill Belichick took a proactive approach in defending his organization Saturday afternoon in Foxborough, Mass.

In an impromptu news conference at Gillette Stadium, Belichick insisted the Patriots did nothing wrong before or during the 45-7 victory over the Indianapolis Colts.

Belichick said the team has conducted its own extensive investigation into the issue, duplicating the preparation process for footballs that the team follows before each game.

"At no time was there any intent, whatsoever, to try and compromise the integrity of the game," Belichick said.

Belichick said he was embarrassed to talk about the inordinate amount of time he has devoted to the issue, especially with the Patriots preparing for a Super Bowl matchup with the Seattle Seahawks.

In what was an often surreal session, Belichick explained the science behind air pressure and how the pressure can change. Belichick said the Patriots prepare a football by raising the air pressure by 1-pound per square inch.

He said the balls were not inflated in a heated room and implied that the weather might have contributed to a change in air pressure.

Belichick said members of his staff and team were unable to detect a difference in balls with a different level of air pressure per square inch.

The news conference took a bizarre turn when Belichick referenced the movie "My Cousin Vinny," saying he's no "Mona Lisa Vito." That character, as Belichick explained, was an automobile expert. Belichick said he's no scientist.

The session later turned testy when Belichick took questions. He had earlier talked about always staying within the rules, so he was asked about the 2007 spying scandal that led to a fine and a loss of a first-round draft pick as punishment.

Belichick, visibly annoyed, said the team filmed a coach giving signals in front of 80,000 people. Later, he said he would no longer discuss the matter.

"This is the end of this subject for me for a long time," Belichick said.

The NFL investigators were at Gillette Stadium on Tuesday and Wednesday, sifting through security video and cellphone data. The league's staff has talked to 40 people, many within the Patriots organization.

But ESPN has reported the league has yet to identify a reason for the improper inflation. The league is not expected to conclude the investigation before the Super Bowl.

The Patriots will be traveling to Arizona on Monday, and Belichick will again meet the media Monday night. Media Day is Tuesday.

Tablets to be used for replay at Pro Bowl

The NFL will test having game officials use tablets for video reviews in Sunday's Pro Bowl.

Coaches and players for the first time have been using the Microsoft Surface tablets on the sidelines all season to look at photos of previous plays.

Having the referee look at replays to determine if calls were correct could lead to the elimination of officials going "under the hood" for instant replay reviews.

"The test in the Pro Bowl gives us the opportunity to see the practicality of the technology in game-time situations, make adjustments or improvements where necessary, and also gauge the usefulness of it to the officials," Troy Vincent, the NFL's football operations chief, said Saturday. "Certainly, we believe it is an enhancement that we would like to integrate in the future."

An NFL staffer will wear a backpack containing wireless radios, and will hold a Surface Pro 3 tablet and headphones during the game.

When a video review is needed, that staffer will hold the tablet and referee John Parry will don the headphones. It is hoped this will speed up the entire process.

If it works well Sunday, this review method won't be a one-off.

"Preseason testing of this technology is very likely," Vincent added. "The process for regular-season use would involve a review and approval by the competition committee."

The powerful competition committee meets in February to present recommendations and proposals to the 32 owners in March at league meetings in Phoenix.

The league also will debut use of real-time video on the tablets for coaches and players to review during the Pro Bowl.

Etc.

The Chicago Bears hired Bo Hardegree as an offensive assistant.

Hardegree follows new Chicago coach John Fox from Denver, where he spent this season as an offensive quality control coach. The Broncos were second in the NFL in scoring offense (30.1 points per game) and fourth in total offense (402.9 yards per game).

Hardegree previously coached at LSU (2011-13) and Duke (2008-10). He was also a quarterback and played tennis at Tennessee, where graduated in 2007 with a degree in exercise science.