The CBI on Thursday questioned Virender Singh Tawde, a doctor and member of rightwing Hindu Janajagruti Samiti, in its ongoing investigation into the murder of Maharashtra anti-superstition activist and rationalist Narendra Dabholkar.
The Central Bureau of Investigation (CBI) officers quizzed Tawde in Mumbai a day after his house in Mumbai's Panvel was searched.
The agency had recovered some material during its earlier searches in connection with the murder case which brought the needle of suspicion on Tawde and Goa blast accused Sarang Akolkar, against whom Red Corner Notice was issued by Interpol in 2012 on request of NIA.
National Investigating Agency (NIA) has been probing the case since after the Goa blast where two people were killed in a bomb explosion on Diwali-eve on October 16, 2009 in the coastal state's commercial capital Margao.
Akolkar's residence in Pune was also searched on Wednesday by the agency which claimed to have recovered several SIM cards, cell phones and data from computer.
CBI officials said that the two came under the scanner after the agency found some "cyber forensic evidence" about their alleged role in the murder case of Dabholkar.
Akolkar, 34, is the key suspect in the murder of Dabholkar, 68, who was gunned down on August 20, 2013, by two unidentified motor-cycle borne assailants near his house when he was out on a morning walk.
Akolkar is believed to be linked to the Sanatan Sanstha, a Hindu right wing organisation whose headquarters are located in Ponda, Goa.
Nearly three years after the brazen daylight murder in full public view, the investigators have yet to ascertain the exact motives behind Dabholkar's murder or identify and zero in on the killers, though some right-wing groups and activists are under a scanner.
Dabholkar's campaign of several decades finally bore fruit when Maharashtra became the first state in the country to enact a full-fledged law against black magic and other superstitious practices, albeit after his death.
The CBI took over the case from Maharashtra Police and filed an FIR on May 9, 2014 on the orders of Bombay High Court which directed the agency considering a PIL filed by former journalist Ketan Tirodkar.