Igor Grechushkin, a Russian businessman based in Cyprus, was detained for possible extradition to Lebanon, where he is wanted for his role in the blast, Bulgarian National Radio and other outlets reported. Authorities in Bulgaria did not comment on the case, but Bulgaria's prosecutor's office said in a statement on Tuesday that it had detained a Russian and Cypriot dual citizen with the initials I.G. "for the purpose of extradition" to Lebanon.