Russia's sports ministry made sure positive urine samples disappeared from late 2011 to 2015 to improve the country's international sporting performance.
It was supported by the country's security service (FSB), the Russian Anti-Doping Agency (Rusada) and the Center of Sports Preparation of National Teams of Russia (CSP),
When this was not enough to hide doping - such as at an international event like Sochi 2014 - positive urine samples were switched with clean ones from a freezer through a "mouse hole", with FSB agents on hand in the Sochi laboratory disguised as maintenance workers.
The claims in detail:
Russia decided to cheat following the "very abysmal" medal count of 15 at the Vancouver 2010 Winter Olympics;
It began making positive drug tests disappear from its anti-doping laboratories in late 2011;
Before the Winter Olympics in Sochi, Russia created a storage bank of clean, frozen urine;
Russia's security service, the FSB, worked in a building next to the Sochi laboratory, swapping positive urine samples for clean negative ones through a "mouse hole", adding table salt to make them weigh the same;
A key FSB agent had access to the Sochi anti-doping laboratory, disguised as a sewage and plumbing contractor;
But, in swapping urine samples, the FSB agents left miniscule tool marks on the bottles - later found by McLaren's investigators using a microscope;
The Moscow laboratory destroyed 8,000 samples it held that were dated prior to 10 September 2014.