The emails containing Peyton Manning’s explanation for the human growth hormone shipments sent to his home went out just after midnight on Dec. 16, 2015.

A few weeks earlier, an investigative reporter with Al Jazeera network informed Manning’s agent that an unidentified source had made a series of allegations about the star quarterback using HGH.

That week, Manning’s lawyers had tried to convince Al Jazeera their source was lying. An Indianapolis clinic had sent HGH to the quarterback’s home in Florida, Manning’s lawyers confirmed — according to documents filed in federal court and interviews with those with knowledge of the discussions — but they said the shipments weren’t meant for Peyton Manning. The HGH was meant for Peyton’s wife, Ashley, who had been prescribed the drug by a doctor who specialized in “anti-aging” medicine, a controversial discipline that espouses disputed theories about the benefits of HGH.

Manning’s lawyers provided Al Jazeera’s lawyers with information about Ashley Manning’s HGH prescription, according to an email obtained by the Washington Post, including her diagnosed conditions and the quantities of HGH she had taken. An Al Jazeera producer then sent a late-night series of urgent emails to medical experts, asking if Ashley Manning’s diagnosis and HGH prescription sounded legitimate.

Eleven days later, Al Jazeera’s documentary, “The Dark Side: The Secret World of Sports Doping,” would feature undercover footage of Charlie Sly, an aspiring pharmacist who worked with a trainer for several NFL and MLB players, claiming he supplied athletes including Washington Nationals third baseman Ryan Zimmerman and retired Philadelphia Phillies first baseman Ryan Howard with banned drugs. In one scene, Sly suggested Peyton Manning ordered HGH under his wife’s name.

Two and a half years later, the documentary remains the subject of ongoing defamation lawsuits against Al Jazeera filed by Zimmerman and Howard, and continues to cause headaches for Manning, now retired. Evidence that has emerged in hundreds of pages of court filings has shed more light on how Al Jazeera produced the documentary, and what its journalists knew about the Mannings before it aired, but has yet to answer the core questions raised by “The Dark Side” — and its critics: Did Al Jazeera catch a “chemical mastermind” who had supplied a bevy of pro athletes with banned drugs, or did it recklessly televise the fabrications of a wannabe drug dealer lying to try to impress a potential client?

In a December 2015 email to medical experts, Al Jazeera producer Jeremy Young included the information lawyers had relayed about Ashley Manning’s ailments and HGH usage.

“Is there any genuine medical justification for treating those conditions with HGH?” wrote Young, who also asked if the situation sounded legal.

The answers from the experts, corroborated by the Post: Ashley Manning’s conditions — withheld from this story at her lawyers’ request — were not treatable with HGH, and her doctor may have broken the law. Because of its rampant abuse by bodybuilders and athletes, HGH is tightly controlled under federal law, and doctors can prescribe the drug legally for only a short list of conditions. While it’s been banned for decades by all major pro sports leagues, the NFL didn’t begin testing for HGH until 2014.

After the documentary aired, as Al Jazeera took criticism for basing explosive allegations on a single source, one of the network’s reporters claimed a second source confirmed the allegations involving Manning.

“We had a second source, absolutely impeccably placed, knowledgeable and credible,” Al Jazeera reporter Deborah Davies said on CNN.

Last week, in court filings, Al Jazeera revealed this source as one of Manning’s lawyers, prompting a confusing series of media reports in which some news outlets incorrectly suggested Peyton Manning had admitted to purchasing HGH under his wife’s name.

In reality, Manning’s lawyers only confirmed Ashley Manning’s HGH prescription. When Al Jazeera’s Davies cited the “second source,” she neglected to mention this source had also strongly denied the HGH shipments to the Manning home were meant for, or taken by, Peyton Manning.

In a phone interview, Matthew D. McGill, lawyer for the Mannings, termed it “unethical and utterly despicable” for Al Jazeera to cite publicly some of the information he had provided in off-the-record discussions as a “second source” for a documentary that suggested Peyton Manning took HGH.

“We went to their lawyers in good faith, we explained that their source was a pharmacy intern who had unlawfully compromised Ashley Manning’s private medical information,” McGill said. “Instead, they exploited her private medical information to raise these baseless innuendos about Peyton. Any notion that we confirmed Sly’s veracity as a source is obviously false, and is beneath contempt.”

Al Jazeera’s attorney, Charles Scheeler, said in a statement that recent court filings referencing the Mannings are redacted, and don’t contain all relevant details of their discussions.

“Al Jazeera stands by its reporting, and wants the whole story told,” Scheeler said. “We invite the Manning parties and Plaintiffs to join Al Jazeera in a request to unseal all court filings in this case. Let’s let the public see the full story and draw their own conclusions.”

The key source

Al Jazeera launched its doping investigation in February 2015, with a sizeable budget and a goal to out high-profile athletes getting an illicit pharmaceutical edge. After seeking the doping expertise of Lance Armstrong (who declined to talk with them) and former BALCO president Victor Conte (who agreed to talk), Al Jazeera journalists settled on a plan to enlist an aging British track star, Liam Collins, to go undercover.

Posing as a middleman for European soccer players in search of a new connection, Collins had no problem catching medical professionals offering banned drugs. But catching high-profile athletes cheating proved more difficult.

In late August, in an email to the investigative team, an Al Jazeera executive producer expressed frustration that reporting trips to France, the Bahamas, Jamaica, Canada, and several cities across the U.S., had yet to deliver evidence of star athletes using banned drugs.

“We now have a ton of hidden camera material in which we’ve identified a key drug supplier and a number of people involved in a drug supply chain . . . But so far we have no supporting evidence of wrongdoing on the part of leading athletes,” executive producer Peter Charley wrote on Aug. 28. “We need to get irrefutable, corroborating evidence implicating athletes.”

In late September, another Al Jazeera supervisor reminded the team a hard deadline was approaching.

“It is a network imperative that we broadcast this investigation this calendar year,” wrote Phil Rees, manager of Al Jazeera’s investigations.

In late October, Al Jazeera team had an apparent breakthrough with Sly, a 31-year-old with an education in pharmacology who worked with professional trainer Jason Riley, who counted Zimmerman, Howard, New York Yankees star Derek Jeter, and many others as clients. (Riley has denied any involvement with banned drugs.)

In a meeting in Sly’s Austin, Texas apartment surreptitiously recorded by Al Jazeera, Taylor Teagarden, a journeyman MLB catcher who last played for the Chicago Cubs, discussed how Sly had helped him get Delta-2, a banned steroid.

A few days later, as Al Jazeera’s Collins accompanied him on several long drives across Texas, Sly listed athletes he claimed he’d supplied with banned substances, including Howard, Zimmerman, and Manning, and particulars of their treatment.

Although Sly had an obvious motive to lie to inflate his doping resume — Collins was posing as a potential client — Al Jazeera’s producers and reporters didn’t make any effort to contact any of the players until Dec. 4, court records show, when the documentary was in editing and 23 days before it was scheduled to air.

That day, reporter Davies sent a wave of emails, including one to Tom Condon, Manning’s agent. The same day, Al Jazeera director of investigative journalism Clayton Swisher boasted to a network executive that the upcoming documentary “stands to be one of our best ever.”

“Our undercover Liam Collins has recorded video and audio . . . that implicates MAJOR American sports icons,” Swisher wrote in email. “The sporting industry is no doubt going to be shaken.”

Confirmation or explanation?

In her email to Condon, Davies did not identify Sly as Al Jazeera’s source, but detailed a list of claims Sly had made about Manning. Among them: that Peyton purchased HGH from a clinic in Indianapolis, had the drugs shipped to his home in Florida under Ashley’s name, spent up to $20,000 a month on HGH, and used the drug so excessively it had caused a “bone development” on his forehead. Davies gave Manning 10 days to respond.

Within days, Manning had hired former White House press secretary and crisis management consultant Ari Fleischer, as well as Gibson Dunn law firm in Washington, which, in turn, hired a private investigations firm to try to identify Al Jazeera’s source.

On Dec. 14, McGill, a partner at Gibson Dunn, emailed Al Jazeera’s lawyers and asked for an extension. The next day, McGill met with two lawyers for Al Jazeera at their office.

Emails between the two legal camps have been included in recent court filings with several redactions, but references to HGH make clear what the lawyers were discussing.

In a Dec. 16 email, Bob Corn-Revere, a lawyer for Al Jazeera, wrote McGill: “One thing that was not clear from our conversation yesterday is how much money the Manning’s spent on HGH . . . Is that something you can share with us off the record?”

A few hours later, Corn-Revere followed up: “To be clear, i wasn’t asking what (in retrospect) may have sounded like a trick question. I wasn’t asking how much Peyton Manning spent on HGH, but was asking what was the total amount spent?”

In McGill’s reply, his discussion of the amount is redacted. That night, Al Jazeera producer Young sent emails to medical experts, detailing the conditions Manning’s lawyers claimed Ashley Manning had been diagnosed with, and the amounts of HGH her doctor had prescribed.

The emails are redacted in court filings. The Post obtained an unredacted version from one of the recipients, Dr. Mark Molitch, a professor of endocrinology at Northwestern medical school.

In phone interviews, Molitch and two other experts agreed that Ashley Manning’s conditions are not among those permitted by the Food and Drug Administration for legal HGH usage. The federal law prohibiting prescribing HGH for unapproved uses is rarely enforced, however, and experts suspect the law is largely ignored by “anti-aging” doctors who believe HGH can reverse the effects of aging.

“The bottom line, however, is it’s still illegal,” said Dr. Thomas Perls, a professor at Boston University medical school.

Dr. Dale Guyer, the Indianapolis physician who prescribed the HGH for Ashley Manning, did not reply to requests to comment.

Sudden reversal

On Dec. 22, five days before “The Dark Side” was set to air, private investigators hired by Manning’s lawyers tracked down Sly in suburban Indianapolis, where he was visiting his parents for the holidays. Two days later, on Christmas Eve, Sly videotaped himself as he read a prepared statement.

“There is no truth to any statement of mine that Al Jazeera plans to air,” Sly said in the video, which he uploaded to YouTube and then emailed to Al Jazeera reporter Davies and Corn-Revere, the network’s lawyer.

The same day, McGill, lawyer for the Mannings, called Al Jazeera’s lawyers to inform them he knew their source was Sly and he was aware Sly had recanted his claims.

In an email to Al Jazeera journalists that afternoon, Corn-Revere recounted the conversation.

“McGill said the Mannings were reserving all their rights, that they would litigate, and that there would be significant adverse publicity about what Al Jazeera knew in advance of the broadcast (including Sly’s recanting),” Corn-Revere wrote.

When “The Dark Side” aired three days later, several of the claims Sly had initially made about Manning — up to $20,000 a month on HGH, and a bone deformity as a result of excessive use — were not included. Left in the program was Sly’s suggestion that Peyton ordered HGH from the Guyer clinic in Indianapolis, where Sly had interned, under Ashley’s name.

Manning never sued Al Jazeera, but the lawsuits filed by Zimmerman and Howard are keeping the retired quarterback involved. Al Jazeera’s lawyers are fighting in court to get records from Manning’s private investigators, in an effort to determine any influence they had on Sly’s recantation statement. McGill, in an interview with the Post, denied any involvement in Sly’s statement.

In the days after the documentary aired, Davies, the reporter, acknowledged in interviews that Al Jazeera had no direct evidence Peyton Manning had taken HGH, and that accusations against Howard, Zimmerman and the others rested entirely on claims Sly had recanted.

Still, Davies said she believed what Sly told her undercover colleague in more than 27 recorded hours over several days was more reliable than his 55-second statement after a visit from two private investigators.

“We’re saying we’ve raised questions,” Davies said in one interview. “And those questions haven’t been answered.”

Rick Maese contributed to this report.