Interpetroleum's CEO Stoil Slavov, who was killed Monday together with his bodyguards, while in the elevator, has been under police investigation since 1997, Interior Ministry officials announced. The investigation, code-titled "The Untouchable", has not yet been closed.
Police has put Slavov and persons connected with him under observation on the occasion of a businessman' abduction in the town of Shumen, northeastern Bulgaria, in 1997. Stoil Slavov was suspected to have participated in the crime.
A prosecution started but later was abandoned because the main witness withdrew his evidence.
Nonetheless, the National Service for Fight Against Organized Crime continued to collect materials and evidence on Stoil Slavov's criminal activities, transforming its investigation from operative into informative.
Stoil Slavov and his bodyguards Petar Petrov, Iliyan Kazakov and Petar Harizanov were identified as the four casualties in the deadly blast on Monday. Nobody claimed responsibility for the attack, which comes after a wave of turf war-connected murders and assaults in the country.