The employee, identified by Turkey’s Anadolu state news agency by his initials M.R.N., is suspected of providing forged travel documents for the assassination’s alleged mastermind, allowing him to return to Iran.
The investigation concerns the gangland-style killing in Istanbul on November 14, 2019 of Masoud Molavi, who had helped run a channel on Telegram called “Black Box” since March 2018.
The encrypted social media channel published corruption allegations against members of the Iranian government, judiciary and intelligence services.
Police at the time said Molavi, who claimed to have contacts within Iran’s Revolutionary Guard, was killed by an assassin who fired a dozen shots.
In a tweet posted a few months before his death, Molavi warned that he was in danger of being killed before he could “eradicate the leaders of this corrupt mafia”.
In December, Turkey’s MIT intelligence Service detained 11 Turks on suspicion of spying and kidnapping another dissident, Habib Chaab, on behalf of Iran.
Tehran accuses Chaab, who was based in Sweden, of being a leading figure of an Arab separatist group known as the Arab Struggle Movement for the Liberation of Ahvaz (ASMLA), which Iran has designated as a terrorist organization.