When Zarco was unable to run because of plantar fasciitis he suggested Santiago should take part using his bib, which has an athlete's identification number printed on it.

The Spaniard went on to run 2 hours 17min 36sec, a time that would have been a Honduran record.

The incident public after the Spanish website Soy Corredor published an article about the change in March 2021, which prompted Santiago, whose personal best for the marathon is 2:09:56, nearly nine minutes faster than Zarco, to tweet an apology, pointing out that he meant no harm.

Zarco later contacted World Athletics to request that the marathon result be attributed to Santiago.

"The fact that Mr Zarco and Mr Santiago exchanged bib numbers and were caught in a public forum demonstrates that their conduct was unreasonable and brought the sport into disrepute," the AIU said in a statement.

"The bib swap was an intentional agreement to alter Mr Zarco's results in the marathon... particularly in circumstances where Mr Zarco must have known that the result in question would have been a Honduran national record."

Both runners then testified at the AIU investigation that Santiago's bag, containing his race bib number, had disappeared just before the race and that they explained to the organisers that Santiago would run with Zarco's bib.

However, the marathon organisers said there were facilities for printing bibs at the starting point and that "no official would have indicated that an athlete could exchange bibs".

The athletes' early admission and their low level of international competition resulted in them benefiting from a shorter suspension period of six months, as opposed to the one-year sanction that the AIU would have requested before a Disciplinary Tribunal.

The case against Santiago can be read here and against Zarco here.