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"We inform that Ihor Andriyovych Ustymenko was dismissed from the SBU Security Service of Ukraine on April 29, 2014," she wrote on Facebook.

"If the journalists asked us about Mr. Ustymenko before their program was broadcast rather than after its airing, maybe there would have been nothing to talk about here," Hitlyanska said.

Read alsoUkraine spy agency 'may have seen planting of bomb that killed journalist' – media (Video)According to her, the murder of Pavel Sheremet is being investigated by the National Police.

The Organized Crime and Corruption Reporting Project (OCCRP) and Slidstvo.info on Wednesday, May 10, released the documentary where they claim an agent working for the SBU was present near the scene when the explosive device was being planted under the driver's seat of a car in which Sheremet was blown up.

The investigation says that Ustymenko had been working for the SBU at least until 2014.