SAN FRANCISCO — Broncos quarterback Peyton Manning reportedly hired private investigators to visit the home of the source that linked him, and other professional athletes, to performance-enhancing drugs in a recent Al Jazeera documentary.

According to the Washington Post, the investigators were dispatched to the residence of Charlie Sly five days before the network’s documentary, “The Dark Side: The Secret World of Sports Doping,” was released. In the film, Sly said he helped professional athletes cheat and also implied that Manning took human growth hormone that was shipped to his wife, Ashley, by an anti-aging clinic in Indianapolis.

The quarterback vehemently denies the claims. Sly, who was unaware at the time that he was being recorded by Al Jazeera, has since recanted.

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According to the Denver Post, Sly’s sister, Kaitlyn, called the police when Manning’s investigators showed up at the Brownsburg, Indiana, home of Sly’s parents, Randall and Judith Sly, on Dec. 22.

The Washington Post also reported that that the investigators were hired to “identify, locate and interrogate Sly” and also sent a lawyer to examine the Mannings’ medical records at the anti-aging clinic, Guyer Institute of Molecular Medicine.

In light of the documentary, Manning hired the crisis management team of former White House press secretary Ari Fleischer. In an interview on Friday with the Denver Post, Fleischer said: “When someone lies about you you don’t take it lying down.”

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Manning repeatedly has called the Al Jazeera report “garbage” and the NFL has said it is in the midst of conducting its own investigation.

“Just like I said in December, I do welcome it,” Manning said, referring to the league’s internal review, on Jan. 28. “I still stand by what I said then . . . It’s garbage from the first day it came out and it’s still garbage today.”

The Broncos quarterback also defended himself in the week leading up to today’s game against the Carolina Panthers in Super Bowl 50.

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”I can’t speak for anybody else,” Manning said on Monday night. “I’ve addressed this before. It’s why I welcome this NFL investigation, because I know the rules of the NFL and I respect the rules, they’re important to me. And so what this report alleges that I did is simply not true. It’s fabricated. It’s junk. It’s garbage. I could give you a long list of other words for it. I can guarantee this investigation, what it will find is an absolute big, fat nothing. That’s how I feel about it.”