A report into claims of doping cover-ups, extortion and money-laundering in athletics will show "a whole different scale of corruption" even compared to Fifa, says co-author Richard McLaren.
The independent commission, set up by the World Anti-Doping Agency (Wada), is set to report its findings on Monday.
McLaren said: "This is going to be a real game-changer for sport."
Meanwhile, the son of ex-IAAF chief Lamine Diack is among four men charged by the body over ethics code breaches.
|Timeline: Athletics doping accusations|
|December 2014: German documentary alleges Russian doping scandal|
|February 2015: Diack says athletics faces 'crisis'|
|August 2015: Coe says IAAF will react robustly|
|August 2015: Wada 'alarmed' by fresh allegations|
Papa Massata Diack is a former consultant to the IAAF (International Association of Athletics Federations), the sport's world governing body.
The charges relate to covering up Russian athlete Liliya Shobukhova's doping violations, the IAAF ethics commission chairman said.
They came in the week that former IAAF president Lamine Diack was placed under investigation by French police, over allegations the 82-year-old took payments for deferring sanctions against Russian drugs cheats.
McLaren, who was appointed by Wada in December 2014 to investigate allegations made in a German TV documentary of systematic doping and cover-ups in Russia, said ahead of Monday's report his team had "found evidence to support what was said in the documentary".
He told the BBC World Service: "We were given a very narrow mandate and asked to look at that documentary and determine the accuracy of it, to what extent it was correct.
"The contents of our report speak for itself, I think."
McLaren, an international sports lawyer who is one of three Wada independent commissioners to have co-authored the document, added they had "absolutely no power" to implement changes, only to make recommendations.
"I'd like to see all of the recommendations adopted and acted on and I'm sure the press will vigilant to seeing that that occurs," he added.
Along with Papa Massata Diack, the other three men charged by the IAAF are: the former head of the IAAF anti-doping department Gabriel Dolle, the former president of the All-Russia Athletic Federation (ARAF) Alexei Melnikov and Valentin Balakhnichev, a former chief ARAF coach for long distance walkers and runners.
The charges were issued in September and announced after new IAAF president Lord Coe won approval to amend the code. Their cases will be heard in London on 16-18 December.
IAAF ethics commission chairman Michael Beloff QC said an investigation was "also ongoing in respect of an additional person".
McLaren added: "You potentially have a bunch of old men who put a whole lot of extra money in their pockets - through extortion and bribes - but also caused significant changes to actual results and final standings of international athletics competitions."
The investigations into the accused officials came about after the independent Wada commission passed on information during their inquiries.