The BBC Eye investigation was not just concerned with the content of the report, but whether it could be trusted as an artefact.

Sometimes, what appear to be official Iranian documents and other materials circulating on the internet are found to have been faked.

Most of these counterfeit documents, however, are easy to spot because they clearly diverge from official formatting - showing erroneous spacing and letter headings, or containing significant grammatical or spelling errors.

They might also include the wrong official slogan or logo for the year they purport to originate from, or an anachronistic title for a government agency or department, for example.

Another indicator is language that does not match the very specific style that tends to be used by Iranian official bodies.

The document our investigation centred on contained a few such inconsistencies. For instance, the "Naja" police force quoted in the report was known as "Faraja" at the time.

Therefore, to further test the document's veracity, we gave it to a former Iranian intelligence officer who has seen hundreds of legitimate ones.

He rang the IRGC archive - using an official code issued each day to senior intelligence officers in Iran - to check if the case file this report was allegedly part of really existed and what it was about.

He received confirmation that it did, and that the report's number showed it was part of a 322-page case file on anti-government protesters in 2022.

While we can never be 100% certain, this gave us confidence that it is genuine.

His unique access to the IRGC also helped us iron out another mystery - the identity of "Naeem 16", the man who told the team to dump Nika's body.

The former intelligence officer did this by making another call - this time to someone inside Iran's military apparatus. He was told Naeem 16 is the call sign for a Captain Mohammad Zamani, serving in the IRGC.

That name is listed as one of the attendees at the five-hour hearing into Nika's death that the report summarises.

We put the allegations to the IRGC and the Iranian government. They did not respond.

The men responsible for Nika's death were not punished, so far as we know.