The spokesperson for one of the hostages, a Kaduna-based cleric, Ahmad Gumi, Tukur Mamu, was arrested in Egypt Tuesday.
He was arrested and detained by Interpol at the Cairo International Airport while awaiting a connecting flight to Saudi Arabia.
The negotiator, Mr Mamu, who is the Publisher of Desert Herald Newspaper in Kaduna, negotiated the release of some of the victims of the March 2022 Kaduna Train attack.
However, according to PREMIUM TIMES Wednesday morning he has been flown back to Nigeria by Interpol after he was interrogated and nothing was found incriminating against him.
He was accompanied by his two wives and one other person.
He is expected to arrive at Aminu Kano International Airport in Kano Wednesday afternoon and may be interrogated further by officials of Nigerian secret police, Department of State Security (DSS).
Mr Mamu announced his withdrawal as the lead negotiator in securing the release of the hostages of the Abuja-Kaduna train attack after he alleged a threat to his life by the Nigerian government.
The terrorists are still holding several of the victims captive.