Kolkata: A team of Narcotics Control Bureau (NCB) officials on May 20 interrogated Mizoram House authorities to verify their reported recommendation of one Mizo to take the rented flat of former Central Bureau of Investigation (CBI) additional director (East) U N Biswas in Salt Lake, from where 24 kgs of controlled psychotropic substances were seized.

NCB sources said that a team, led by senior officials of the Bureau, had also fanned out in different parts of the metropolis in connection with the seizure of ephydrine hydrochloride, used for making heroin substitute amphetamine type stimulant, from the ground floor flat of Biswas' house on May 17.

To a question, the NCB sources said that the former CBI additional director had already been interrogated, ''and if necessary, we will further talk to him''.

However, the narcotics bureau sleuths refused to divulge anything on any development of the inquiry process.

According to the sources, record books of Mizoram House were also checked to find out the whereabouts of N Thenga, the Mizo who had rented the flat of Biswas in February, but remained traceless since May 17.

The NCB officials were also in touch with the Mizoram government to trace Thenga, adding that the investigations were in progress.

''We have been investigating, on the basis of Biswas' statement to NCB after the arrest of five foreigners and seizure of the controlled psychotropic substance, as also on our own lines of inquiry into the case,'' they added.

Acting on a tip-off from the US Drug Enforcement Agency, the NCB sleuths raided the premises of Biswas and arrested five foreigners – two Chinese and three Myanmarese – alongwith the haul.

PTI