In January 2020, an undercover documentary aired on German TV which made serious allegations of financial malpractice and corruption of Anti-Doping Procedures against Aján.

This led to him resigning as an IOC honorary member[4] and temporarily stepping aside as president whilst an investigation, headed by professor Richard McLaren, was carried out.

In a leaked email after stepping aside, it was alleged that Aján had made 'insults and implicit threats' to IWF interim-president Ursula Papandrea, including to have her arrested.

Aján himself was said to have gained his re-election as president through vote buying on multiple occasions and his own son-in-law was the Director General of the IWF at the time of the investigation.

[9] The reports findings also concluded that Aján personally collected all anti-doping violation fines and that there was around $10.5 million unaccounted for in the IWF's accounts, as well as 41 positive doping tests that were covered up and 130 that were never processed,[10] including two athletes who had won gold and silver medals at world championships.

One instance in the report stated that members from the Albanian Weightlifting Federation drove from Tirana to Budapest with nearly $75,000 cash to pay an Anti-Doping fine to Aján so that Albania would not be banned from competing at the 2016 Olympics.