The chemist has kept a diary most of his life. His daily habit is to record where he went, whom he talked to and what he ate. At the top of each entry, he scrawls his blood pressure.

Two of his hardback journals, each embossed with the calendar year and filled with handwritten notes from a Waterman pen, are now among the critical pieces of evidence that could result in Russia being absent from the next Olympic Games.

The chemist is Grigory Rodchenkov, who spent years helping Russia’s athletes gain an edge by using banned substances. His diaries cataloging 2014 and 2015 — his final years as Russia’s anti-doping lab chief before he fled to the United States — provide a new level of detail about Russia’s elaborate cheating at the last Winter Games and the extent to which, he says, the nation’s government and Olympic officials were involved.

His contemporaneous notes, seen exclusively by the New York Times, speak to a key issue for Olympic officials: the state’s involvement in the massive sports fraud. In recent days, it has become clear that the International Olympic Committee is convinced of the authenticity of the notes and that they are likely to contribute to the group’s decision to issue severe penalties.

Olympic officials will announce their decision Dec. 5. If they do not bar Russia completely from the coming Winter Olympics in Pyeongchang, South Korea, they are likely to keep all Russian emblems out of the games: The Russian flag would not fly at the opening and closing ceremony, Russian athletes would compete in neutral uniforms and the Russian anthem would not be played. Such restrictions, Russian officials have said, would be tantamount to an outright ban, and Russia would consider boycotting the 2018 Olympics.

“The Disciplinary Commission does not consider it at all likely that these pages were newly re-written or that, at the time, Dr. Rodchenkov misrepresented the reality in his own way,” an IOC document published Monday said. “These entries may therefore be considered as a significant evidential element.”

Together with Rodchenkov’s sworn statements, the diaries detail specific discussions about cheating he had with prominent officials including Vitaly Mutko, Russia’s sports minister at the time who is now the nation’s deputy prime minister; Yuri Nagornykh, Mutko’s former deputy sports minister, who also belonged to Russia’s Olympic Committee; and Irina Rodionova, the former deputy director of the center of sports preparation of national teams of Russia.

Alongside those consequential conversations, Rodchenkov recorded the mundane details of his life — simple errands like buying a Bounty chocolate bar at Sochi’s central market along with cold medicine for Thierry Boghosian, the international lab inspector who never detected Russia’s brazen breaches of drug-testing during the three weeks of the Games.

On Jan. 13, 2014, Rodchenkov wrote that Rodionova’s assistant, Aleksey Kiushkin, had brought him a drug cocktail known among the officials as Duchess, a mixture of three anabolic steroids and Martini-brand vermouth. Rodchenkov had formulated the drink for top athletes to take throughout the Olympics, and Rodionova prepared and distributed it to coaches and athletes.

“Kiushkin came with tons of news. He also brought a freshly-made Martini. I took it right away,” wrote Rodchenkov, who regularly tested drugs on himself and documented their effects.

For the following week, as the Sochi Games approached, alongside admirations of his new Samsung smartphone and criticisms of Olympic cafeteria food, Rodchenkov recorded his frustration that officials had not clearly outlined their plans to transport from Moscow the hundreds of ounces of clean urine that top athletes had for months collected in baby food jars and old soda bottles — urine that was the linchpin to what he repeatedly referred to as “the Sochi plan.”

On Feb. 3, four days before the Sochi Games began, Rodchenkov’s preparations culminated with his presentation to Mutko, the sports minister. In a meeting at Mutko’s office at the local organizing committee’s headquarters, Rodchenkov wrote that day, he had handed Mutko a copy of the “Duchess list,” naming the dozens of Russian Olympians who were ingesting the drug cocktail and would have their incriminating urine swapped out with their prestocked clean urine.

Following multiple investigative reports published last year, Russia’s coordinated cheating has been accepted as fact among top Olympic officials, despite a largely defiant response from Russian authorities that has grown fiercer in recent weeks. This fall, Russia criminally charged Rodchenkov with abuse of authority and indicated it would request his extradition. Authorities had previously seized his property in Moscow, where his family remains.

Russian officials have suggested Rodchenkov acted alone in tampering with more than 100 incriminating urine samples in Sochi, an act which has so far led the global officials to order Russia to return 11 Olympic medals. “One can hardly steal a victory that has already been won,” a Kremlin spokesman said Monday about those disqualifications.

President Vladimir Putin has forcefully disputed the state’s involvement, a question that could be the difference between a full ban of the nation’s athletes and a lesser punishment, such as barring the Russian anthem from playing at the 2018 Games.

But consequences are expected to extend beyond the Winter Games, as the widespread cheating that investigators confirmed stretched across seasons, sports and years — as Rodchenkov also closely detailed discussing with Russia’s most powerful sports officials in his journals.

Rodchenkov was watching television on Jan. 8, 2014, when the deputy minister called to reprimand him after a star racewalker, Elena Lashmanova, had been caught doping. “Nagornykh called — he’s calling everyone on the carpet,” Rodchenkov wrote. “I came to the ministry, waited for Nagornykh, had a 2-hr discussion about details of the Sochi prep.”

Months later, on March 14, 2014, Rodchenkov wrote that he had sat in his car, charging his phone, while talking to Mutko, who had called to “let me have it” for not effectively covering up Lashmanova’s drug use.

On April 21, 2014, Rodchenkov debated with Nagornykh whether to falsify the star athlete’s record, something the deputy minister was advocating but Rodchenkov feared would draw the attention of global regulators and jeopardize his lab’s accreditation, he said.

“He got an excellent tan in Mexico,” Rodchenkov wrote after meeting with Nagornykh at the sports ministry that day. “I spent 1.5 hours there fighting. Nagornykh slowly backed off. We agreed to go see Mutko by 1:00.”

In July 2014, Lashmanova was suspended.

Last year, after an initial investigation commissioned by the international regulator of drugs in sports had confirmed Rodchenkov’s account, the Russian government dismissed Nagornykh, Zhelanova and Rodionova. Putin elevated Mutko to deputy premier in October 2016.

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