In a major blow to Tom Brady’s golden reputation, a National Football League investigator concluded Wednesday that the Patriots quarterback most likely participated, at least tacitly, in violating the sport’s integrity by using improperly deflated footballs as he guided the team toward a Super Bowl championship.

A 243-page report on the NFL’s inquiry identified two low-level Patriots employees as the alleged chief conspirators in the scandal and cited “substantial and credible evidence’’ that Brady was “at least generally aware of the inappropriate activities,’’ — despite his insistence to the contrary.

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“We found [Brady’s] claims not plausible and contradicted by other evidence,” the NFL’s report said.

One of the two Patriots workers, a part-time attendant named Jim McNally, described himself in a text recovered by investigators as “the deflator,’’ the report found.

Brady and the two men appear to have been caught in a web of evidence that ranged from security video footage of McNally suspiciously ducking into a bathroom with a bag full of footballs moments before delivering them to the field, to Brady and the other worker engaging in apparent damage-control calls and texts as soon as reports broke of the purported cheating.


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No other member of the Patriots organization, including owner Robert Kraft and coach Bill Belichick, was implicated as a result of the 15-week inquiry. But the findings cast a cloud over the franchise’s fourth Super Bowl title of the century in February, just as the 2007 Spygate affair tainted previous triumphs.

NFL Commissioner Roger Goodell, a close friend of Kraft’s, directed Troy Vincent, the league executive in charge of football operations, to consider disciplinary action, which could include a fine or suspension for Brady.

Kraft, who earlier professed the franchise’s innocence, lambasted the findings, though he said he will not appeal them and will accept any penalties.

The inquiry centered on allegations that the Patriots used underinflated footballs in January while defeating the Indianapolis Colts, 45-7, in the American Football Conference championship game to advance to the Super Bowl. Brady has said he prefers balls with lower inflation levels because they are easier to grip and throw.

“To say we are disappointed in the findings, which do not include any incontrovertible or hard evidence of deliberate deflation of footballs at the AFC Championship Game, would be a gross understatement,’’ Kraft said in a statement. “While I respect the independent process of the investigation, the time, effort and resources expended to reach this conclusion are incomprehensible to me.’’

The NFL’s findings are based almost entirely on circumstantial evidence, and while investigators appeared to build a persuasive case that inappropriate activity occurred, Kraft suggested there was no smoking gun linking Brady to cheating.

Brady — who refused to provide his e-mails, text messages, and phone records to league investigators — has not publicly addressed the controversy, which has come to be known as “Deflategate,” since an uncomfortable news conference in January when he was asked directly, “Are you a cheater?’’

“I don’t believe so,’’ he replied. “I mean, I feel I always played within the rules.”

He also rejected the notion that others had acted on his behalf. “I am very comfortable saying nobody did it, as far as I know,” Brady said then.

Video: Tom Brady says he did not alter the footballs in Colts game

But his denials in an interview with the NFL investigators ultimately seemed to fall flat.

“We found [Brady’s] claims not plausible and contradicted by other evidence,” the report said.

Brady was not available Wednesday. But his father, Tom Brady Sr., was quoted by USA Today as portraying him as a victim of “Framegate.’’

“I don’t have any doubt about my son’s integrity — not one bit,” the elder Brady said. “In this country, you’re innocent until proven guilty. It just seems Tommy is now guilty until proven innocent.’’

Brady’s next scheduled public appearance is a speaking engagement Thursday at Salem State College.

The report alleges that McNally, who served as the locker room attendant at Gillette Stadium for NFL officials, and John Jastremski, a Patriots equipment assistant, probably engaged in “a deliberate effort to release air’’ from the footballs after a referee examined them before the game.

Attempts to reach Jastremski were not successful. When a Boston Globe reporter seeking a comment knocked at McNally’s home in Amherst, N.H., a man standing behind a curtain said, “Get off my land right now.’’

The evidence against Brady included text messages between McNally and Jastremski in the three months before the AFC title game. Some texts allegedly implied Brady requested his footballs be deflated below the league’s minimum standard of 12.5 pounds of pressure per square inch.

Investigators alleged the texts showed Brady was not pleased with the quality of some game balls the attendants had prepared. In one text, McNally complained to Jastremski, “Tom sucks . . . im going [to] make that next ball a [expletive] balloon.’’

Jastremski’s alleged reply: “Talked to him last night. He actually brought you up and said you must have a lot of stress trying to get them done.’’

The report includes numerous text references to McNally allegedly wanting Brady to sign memorabilia in exchange for deflating balls.

“Remember to put a couple sweet pig skins ready for tom to sign,” McNally allegedly texted Jastremski.

The report states, “Taking the text messages as a whole, Brady is a constant reference point in the discussions between McNally and Jastremski about inflation, deflation, needles, and 18 items to be received by McNally.’’

Citing videotape evidence and witness interviews, the report alleges that McNally inappropriately removed the Patriots game balls from the officials locker room before the AFC title game and carried them into a restroom near the entrance to the field. He allegedly locked the door and remained there for about 1 minute and 40 seconds before he delivered the balls to the field.

A scientific consultant hired by the NFL investigators simulated the time it would take to reduce the pressure in 13 footballs by using a needle, and the time was “well under one minute and forty seconds,’’ according to the findings.

The report states that Colts general manager Ryan Grigson alerted the NFL before the game to be aware of the Patriots possibly deflating footballs. And after one of Brady’s passes was intercepted in the first half, the Colts tested the ball and told officials it was underinflated.

That prompted the officials to test 11 of the Patriots footballs at halftime, and each one was found to be inflated below the league minimum, the report states. Four Colts balls were tested and deemed legal.

Soon after the first news stories about the Patriots’ alleged wrongdoing broke on Jan. 19, Brady and Jastremski engaged in a number of telephone and text communications investigators cite as additional evidence that Brady was aware of the inappropriate activity.

Brady and Jastremski had not communicated by phone or text for more than six months before then. But at 7:26 a.m. on Jan. 19, the morning after the AFC title game, they spoke by phone for the first of six times over the next three days, their conversations lasting a total of more than 55 minutes.

The report alleges Brady also invited Jastremski to his office at Gillette Stadium, and investigators said Brady sent Jastremski text messages apparently aimed at calming him. “You good Jonny boy?’’ one text from Brady allegedly read. “Still nervous; so far so good though,’’ Jastremski wrote back, according to the report.

Brady and Jastremski then allegedly contradicted each other in interviews with investigators. Brady, while denying any knowledge or involvement in wrongdoing, told the investigators he did not know McNally’s name or his game-day duties.

However, Jastremski told investigators Brady did know McNally’s name and his game-day responsibilities, the report states. In addition, McNally was said to have told NFL security officials that Brady personally told him which inflation level he preferred for his footballs.

Investigators complained the Patriots refused to make McNally available for a final interview on “important topics,’’ a complaint that Kraft said “offended’’ him. “What the report fails to mention is that he had already been interviewed four times and we felt the fifth request was excessive for a part-time game-day employee who has a full-time job with another employer,’’ Kraft said.

Regarding the number of times McNally was interviewed, the report states only that the team counsel refused to make McNally available for “a follow-up interview” regarding what investigators deemed “important topics.”

The investigation, led by Theodore V. Wells Jr., a private attorney commissioned by the NFL, included analysis by scientific consultants who concluded that no other factor such as weather caused the Patriots’ balls to deflate.

Kraft took exception to the finding that weather played no role. “Based on the explanations I have heard and the studies that have been done, I don’t know how the science of atmospheric conditions can be refuted or how conclusions to the contrary can be drawn without some definitive evidence,’’ he said.

Investigators interviewed more than 65 witnesses, including Belichick.

Stan Grossfeld of the Globe staff contributed to this report. Bob Hohler can be reached at robert.hohler@globe.com.