ATLANTIC CITY, N.J. -- A law enforcement official says he sent a video of Ray Rice punching his then-fiancée to an NFL executive five months ago, while league executives have insisted they didn't see the violent images until this week.

The official played The Associated Press a 12-second voicemail from an NFL office number on April 9 confirming the video arrived. A female voice expresses thanks and says: "You're right. It's terrible."

"We are not aware of anyone in our office who possessed or saw the video before it was made public on Monday. We will look into it." NFL spokesman Brian McCarthy

Hours after the report Wednesday, Goodell announced former FBI director Robert S. Mueller III will conduct a probe into how the league pursued and handled evidence as it investigated claims against Rice.

NFL spokesman Greg Aiello said in a statement that the investigation will be overseen by owners John Mara of the New York Giants and Art Rooney of the Pittsburgh Steelers. Goodell said that Mueller will have access to all NFL records and will have full cooperation from league personnel.

The law enforcement official, speaking to the AP on condition of anonymity because of the ongoing investigation, says he had no further communication with any NFL employee and can't confirm anyone watched the video. He said he was unauthorized to release the video but shared it unsolicited because he wanted the NFL to have it before deciding on Rice's punishment.

The NFL has repeatedly said it asked for but could not obtain the video of Rice hitting Janay Palmer -- who is now his wife -- at an Atlantic City casino in February.

The league says it has no record of the video and that no one in the league office had seen it until it was released by TMZ on Monday. Asked about the voicemail Wednesday, NFL officials repeated their assertion that no league official had seen the video before Monday.

"We have no knowledge of this," NFL spokesman Brian McCarthy said Wednesday. "We are not aware of anyone in our office who possessed or saw the video before it was made public on Monday. We will look into it."

Goodell, who was supposed to attend an award ceremony for Panthers owner Jerry Richardson in Charlotte Wednesday night, did not attend the event and instead changed his plans and headed back to New York.

The law enforcement official said he sent a DVD copy of the security camera video to an NFL office and included his contact information. He asked the AP not to release the name of the NFL executive, for fear that the information would identify him as the source.