Complete the following sentence: In February 2004, Rybkin disappeared for 4 days under mysterious circumstances. <unk> <unk> <unk> <unk>
1999 bombings in Moscow that led to a war in the Russian breakaway republic of Chechnya<unk> <unk> <unk> <unk> ️<unk>️<unk>️<unk>️<unk>️<unk>️ Upon arrival he was offered refreshments in the apartment, at which point he became "very drowsy".<unk> Upon arrival he was offered refreshments in the apartment, at which point he became "very drowsy".<unk> ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ According to Alexander Litvinenko, the FSB agents apparently treated Rybkin with their standard truth drug.<unk> According to Alexander Litvinenko, the FSB agents apparently treated Rybkin with their standard truth drug.