TORONTO • A discreet "mouse hole" through a wall, surreptitiously tampered samples using table salt and night-time visits by Russian secret service agents dubbed "the magicians".
The revelations detailed in a damning 100-page report released on Monday, alleging Russian state-run doping at the 2014 Sochi Winter Olympic Games and other major sports events, read like a Cold War thriller.
The probe by Canadian law professor Richard McLaren for the World Anti-Doping Agency found that the Federal Security Service (FSB) - the successor to the notorious KGB - helped "the state-dictated fail-safe system" carried out under the Moscow sports ministry and covering 30 sports.
Homing in on the Sochi Games, McLaren's report states: "The FSB was intricately entwined in the scheme to allow Russian athletes to compete while dirty."
Central to the plan was destroying the supposedly tamper-proof urine samples that would have seen a Russian athlete caught doping and swopping them for clean ones.
The ploy involved a "clean urine bank" that was full of Russian competitors' samples and later secretly transported by the FSB from Moscow to an FSB building located handily next to the Sochi Olympic testing laboratory, the report said.
"The bank of clean urine sat in storage awaiting the swapping programme at Sochi when required."
The report said it had credible evidence from Moscow's former anti-doping laboratory director Grigory Rodchenkov about what happened next - it was his allegations that sparked the investigation.
According to him, samples provided by athletes would pass through the "mouse hole" around midnight inside the supposedly secure Sochi laboratory into an adjacent "operations" room outside the secure perimeter.
From there an FSB agent disguised as a sewer engineer who had security clearance to enter the laboratory stepped in.
The agent would dispose of the dirty urine and replace it with a clean sample taken from the FSB freezer next door, the caps and stoppers screwed back into place, before returning it back through the hole for testing the next morning - what the report dubbed a "quaint solution".
Rodchenkov's role included manipulating the substituted sample - including by using salt - so the ruse would not come to light.
"The Sochi sample swopping methodology was a unique situation, required because of the presence of the international community in the laboratory," the report said, adding that forensic examinations confirmed sample bottles had been tampered with.
"It enabled Russian athletes to compete dirty while enjoying certainty that their anti-doping samples would be reported clean."
The investigation also alleged how, as part of the wider subterfuge, thousands of dirty samples were hastily destroyed to avoid detection.
Rodchenkov also held an urgent meeting with deputy sports minister Yury Nagornykh - accused of being central to the Sochi cover-up - over athletes whose samples were "potentially a problem if another accredited laboratory were to analyse them".
"The upshot of that meeting was that deputy minister Nagornykh resolved to call in the 'magicians'," the report said.