The threat to progressive thinkers in society loomed large as long as the masterminds of rationalist Dr. Narendra Dabholkar’s murder were roaming free, said the Maharashtra Andhshradha Nirmulan Samiti (MANS) on Friday.The MANS, founded by the rationalist in 1989, will launch a campaign called ‘Jawab Do’ (give us the answers) on August 20 — the sixth anniversary of Dabholkar’s death — to demand the arrest of the masterminds.“After the Bombay High Court rapped the Central Bureau of Investigation (CBI) for dragging its feet over the probe, the agency finally arrested Sachin Andure and Sharad Kalaskar last year and named them as Dabholkar’s assailants. At the time, we had hoped that the case would finally see a speedy conclusion with the masterminds being brought to book. Regrettably, nothing of the kind has happened so far,” Dr. Hamid Dabholkar, MANS activist and son of the late rationalist, said.He said Dabholkar’s killers had no personal quarrel with him, but were incited by certain people on the basis of differences with the rationalist’s way of thinking and his ideas. “So, it is all the more urgent that the masterminds of this crime, who are responsible for this murder, be nabbed by the CBI,” Dr. Hamid said, alleging a lack of political will on part of the State government in probing the case.He said that from the evidence gathered by investigating agencies and the charge sheet filed by the CBI, it was reasonably certain that the crime was linked to the murders of Communist leader Govind Pansare in Kolhapur, scholar M.M. Kalburgi in Dharwad and journalist Gauri Lankesh in Bengaluru and that all four killings were committed by members of an ideologically hard-line outfit.“Despite this, it seems that the State government is not interesting in probing these radical organisations. The High Court has also repeatedly ticked off the CBI for its tardiness in retrieving the alleged murder weapons that are believed to have been dismantled and thrown by the assailants in a creek near Mumbai. We also demand that the agencies take action in that regard,” Dr. Hamid said.He said that as the CBI delayed in filing a charge sheet against Amol Kale, Rajesh Bangera and Amit Degvekar in the Dabholkar case, the trio was able to secure bail. All three are prime accused in the Gauri Lankesh murder and are lodged in Bengaluru’s Central Prison. The MANS will also launch a social media campaign tagging Chief Minister Devendra Fadnavis and Prime Minister Narendra Modi to demand the arrest of the mastermind.Dr. Hamid said the Dr. Narendra Dabholkar Memorial Lecture will be delivered by N. Ram, chairman, The Hindu Group, on August 20 at the Tilak Smarak Mandir in Pune. “Mr. Ram will be speaking on three challenges facing current Indian society: the assault on reason, the erosion of free speech and the reality of mass deprivation,” he said.Dabholkar was shot by assailants during his morning stroll at the Omkareshwar Bridge in Pune on August 20, 2013. Pansare and his wife, Uma, were similarly shot at close range from two 7.65-mm country-made weapons while they were returning from a morning walk outside their home in KolhapurThe similar nature of the murder of Kalburgi outside his home in Dharwad and of Lankesh in Bengaluru has led several activists to believe that the killings were part of a pre-planned fundamentalist, right-wing Hindutva conspiracy.