Adam Schefter discusses the findings of an independent investigation led by Robert Mueller, who deemed the NFL had never previously seen the Ray Rice in-elevator video. (3:10)

The NFL was deemed to have never seen the Ray Rice in-elevator video before the public saw it, according to findings released Thursday by an investigation led by former FBI director Robert Mueller.

"We found no evidence that anyone at the NFL had or saw the in-elevator video before it was publicly shown. We also found no evidence that a woman at the NFL acknowledged receipt of that video in a voicemail message on April 9, 2014," the report said.

The Associated Press originally reported that a law enforcement official showed the AP the video and played for it a 12-second voice mail dated April 9 in which a woman verifies receipt of the video.

Although the findings supported commissioner Roger Goodell's assertion that the league had not seen the video that shows Rice, the former Baltimore Ravens running back, punching his then-fiancée, Janay Palmer, in an Atlantic City elevator, the Mueller report did say the NFL could have done more to properly investigate the charges.

"We concluded there was substantial information about the incident -- even without the in-elevator video -- indicating the need for a more thorough investigation," the report said. "The NFL should have done more with the information it had, and should have taken additional steps to obtain all available information about the February 15 incident."

The report also said the NFL failed to:

• Contact police officers who investigated the incident, the Atlantic City Prosecutor's office or the hotel to obtain or view the in-elevator video.

• Ask Rice or his lawyer whether they would make the tape available.

• Follow up with the Ravens to determine whether they had additional information after the league's initial contact with the team.

Roger Goodell's assertion that no one at the NFL's league office had previous knowledge of the Ray Rice video was proved true by the Mueller report. AP Photo/Eric Risberg

In response to the report's findings, a joint statement was released by New York Giants president John Mara and Pittsburgh Steelers president Art Rooney II, whom the league picked to oversee Mueller's investigation.

"As owners, we are the first to agree that the NFL did not have a sufficient policy in place to deal with players or other personnel accused of domestic violence," the statement read in part. "... We were slow to react, and in the case of Ray Rice, the original punishment was insufficient. In addition, the steps taken by the NFL to investigate this matter were inadequate. Since then, a new policy concerning domestic violence and other rules for conduct violations have been put into place. We believe these new policies are tough and appropriate."

The joint statement also said NFL owners are confident that Goodell "is the right person to lead the league as we move forward."

In a conference call, Mara also said that what has transpired has served as a wake-up call for the league, a sentiment that was shared by Goodell on Thursday.

"While this investigation has now concluded, our focus on the underlying issues and our commitment to positive change remain as strong as ever," Goodell said in a statement. "We have all learned a great deal in the past months and expect to be judged by how we lead going forward on issues of domestic violence and sexual assault."

Dallas Cowboys owner Jerry Jones also threw his support behind Goodell but added, "I would hope that certainly something like this report would accentuate the transparency that the commissioner wants and that the owners want."

The Ravens also released a statement Thursday afternoon.

"More than anything, the report reminds us all of the gravity of the consequences of intimate partner abuse and the lessons we must all learn," Ravens president Dick Cass said in the statement. "We have taken steps to educate ourselves, and others, about this important issue, and will continue to do so."

While acknowledging that the NFL has made strides to improve its personal conduct policy, the report offered additional suggestions, including the creation of a specialized investigative team for domestic violence and sexual abuse cases.

According to the Mueller report, the AP did not reveal the name of the official who showed it the video and voice mail, nor did the AP provide the official's phone number to investigators. Investigators working with Mueller did not make contact with the man. He told the AP he took steps to avoid being found or identified by the NFL.

"I took steps to ensure a call from any person at the NFL wouldn't be traced back to me and I was never contacted by the team of investigators hired by the NFL to investigate the NFL," the official told the AP. "I still don't know who confirmed receiving the video, and I don't know what that person did with it."

In addition, according to the Mueller report, the Atlantic City Police Department, which obtained video footage from the hotel and had a detailed recounting of the in-elevator video from one of its lieutenants, declined to make any of its employees available for interviews or written questions.

Information from The Associated Press and ESPN.com's Dallas Cowboys reporter Todd Archer was used in this report.