On his return, he faced further questioning by investigators.[1] On 19 July, an official explanation was published in Vremya, blaming the disaster entirely on the operators and local management.[2] The true causes of the accident was classified by the KGB.[2] On hearing the news on TV, Bryukhanov's mother collapsed from a heart attack and died.[2] Bryukhanov was charged on 12 August and imprisoned by the KGB.