"The NFL should have done more with the information it had and should have taken additional steps to obtain all available information about the Feb. 15 incident," Robert S. Mueller III said in a statement after releasing his report.
Mueller found the NFL's deference to the law enforcement process involving Rice "led to deficiencies in the league's collection and analysis of information during its investigation. He added such an approach "can foster an environment in which it is less important to understand precisely what a player did than to understand how and when the criminal justice system addresses the event."
Mueller said he can find no evidence the league received the video showing Rice striking his fiancee in a casino elevator before it was published online in September. A law enforcement official showed The Associated Press videos of the incident and said he mailed a DVD to NFL headquarters in April.
The report said a review of phone records and emails of NFL employees in New York backs up statements from Commissioner Roger Goodell that nobody had seen the video before the league initially suspended Rice.
The private investigation without subpoena power did not include any contact with the law enforcement official who showed the AP video of the incident. The officer backed up his claims by playing the AP a 12-second voicemail from an NFL office number dated April 9, in which a woman verifies receipt of the video and says: "You're right, it's terrible."
The official, who insisted on anonymity because he was not authorized to share the video, says he took steps to avoid being found or identified by the NFL.
"We have reviewed the report and stand by our original reporting," said Kathleen Carroll, the AP's executive editor.
"The Mueller team did ask us for source material and other newsgathering information, but we declined. Everything that we report and confirm goes into our stories. We do not offer up reporters' notes and sources."
Mueller's report details some of the efforts the NFL made in obtaining the video, but said the league should have taken additional steps to find out what happened inside the elevator.
"League investigators did not contact any of the police officers who investigated the incident, the Atlantic County Prosecutor's Office, or the Revel to attempt to obtain or view the in-elevator video or to obtain other information," the report said. "No one from the League asked Rice or his lawyer whether they would make available for viewing the in-elevator video they received as part of criminal discovery in early April."
The report also said the league didn't follow up on initial conversations with the Ravens to determine whether the team had more information.
The official showed the AP multiple videos from the casino the night Rice was arrested. Those videos included security cameras from inside and outside the elevator and two cellphone videos that included some audio.
The league said it considered the video published by TMZ in September to be new evidence meriting an indefinite suspension. Its emergence drew renewed backlash to the league from women's organizations, members of Congress and players — all calling for more detail on how the NFL handled the case.