Back in late December, a report from Al-Jazeera linked six NFL players to human growth hormone or performance-enhancing drugs. After the report came out, NFL commissioner Roger Goodell announced that the league would launch an investigation into its veracity. Earlier this month, the NFL accused the NFLPA of stalling the investigation.

"We have pushed to do them sooner," NFL spokesman Joe Lockhart told The MMQB. "[The union has] articulated some reasons why they can't be done right away."

On Friday afternoon, USA Today reported that four of the players -- Packers linebackers Clay Matthews and Julius Peppers, Steelers linebacker James Harrison, and former Packers linebacker Mike Neal -- will be interviewed about the allegations in the coming weeks. Matthews, Peppers, and Harrison are scheduled to be interviewed on the first day of training camp, while Neal will be interviewed on or before July 22.

A letter was sent from Adolpho Birch to NFL counsel Heather McPhee on the subject, that read in part:

"On January 11, 2016, the league notified Messrs. Peppers, Neal, Matthews and Harrison that it had initiated an investigation following the airing of the Al-Jazeera America documentary, which raised serious issues concerning their possible violation of the NFL/NFLPA Policy on Performance-Enhancing Substances.

The players were further advised that, with their full and timely cooperation, the investigation would be conducted expeditiously and with minimal disruption.

While the investigation has proceeded, we have yet to interview the players.

We have attempted since early April to work through the NFLPA to schedule them, but despite multiple requests the NFLPA has failed to respond, except to seek reconsideration of the basis for the investigation.

This continuing delay and avoidance has obstructed our ability to conduct and conclude the investigation.

In fairness to all, including the players involved, we must move forward with the interviews.

Accordingly, this will advise that the interviews of Messrs. Peppers, Matthews and Harrison will be scheduled for the first day of their respective training camps, and the interview of Mr. Neal (free agent) will take place on or before July 22.

The players will be advised of the specific scheduling details by separate correspondence on which the NFLPA will be copied, and of course an NFLPA representative may attend each interview should the player so request."

An NFLPA spokesman gave USA Today no comment on the matter.