The family members -- Dr Megha Pansare, Smita Pansare, Adv Kabeer Pansare -- wrote the detailed letter to Superintendent of ATS, Pune division, Jayant Meena and put forth several pieces of information, Deccan Herald reported.

The letter came weeks after the Bombay High Court directed the agency to probe the fresh details that the Pansare family would said it would provide in connection with the killing of Govind Pansare.

A rationalist, trade unionist, social activist and a leader of the Communist Party of India, Govind Pansare, along with his wife -- Uma -- were attacked in Kolhapur by two youths on a motorcycle on February 16, 2015. Four days later, he died at Mumbai's Breach Candy Hospital.

The letter said, "Comrade Pansare was bitterly opposed by right-wing Hindutva organisations such as Sanatan Sanstha, Hindu Janjagruthi Samiti, etc, for his ideologies of secularism, rationality, equality, and lifelong work of uplifting the marginalised and authoring books like Shivaji Kon Hota?"

The Pansary family reiterated the role of Sanatan Sanstha founder Dr Jayant Athavale, leader Virendra Marathe and others in the Pansare murder case and demanded that "necessary steps" be against them.

Reportedly, the letter also drew similarities from the murders of Dr Narendra Dabholkar, Professor MM Kalburgi and journalist Gauri Lankesh, linking them with that of Govind Pansare.

"We would like to draw your attention to the five chargesheets filed in the case of Comrade Pansare. Twelve persons have been arrayed as accused. Two of the twelve accused have been declared absconding. All accused are members of Sanatan Sanstha and/or Hindu Janjagruti Samiti and some of the accused are also named in the murder cases of Dr Narendra Dabholkar, Prof MM Kalburgi and Gauri Lankesh and Nalasopara weapons seizure case, and other related cases, which proves that there exists the a common link," the letter was quoted by the Deccan Herald.

'Organised Terrorist Network Of Criminals'

The Pansare family claimed that the ATS and other probe agencies like the Central Bureau of Investigation, Maharashtra Police, Karnataka and the Goa Police have knowledge about the role of Sanatan Sanstha and its "sadhaks" in the four murders and other such heinous crimes.

"However, for reasons best known to the investigating agencies, this angle has not been examined," they said, adding that it was important to do so, calling the people governing it as "an organised terrorist network of criminals acting under the guidance and directions" of Jayant Athavale and Virendra Marathe.

Maharashtra ATS had in 2018 seized large numbers of pistols, bombs and explosives in the Nalasopara explosives seizure case. The chargesheet, which it filed on February 18, 2019, was against twelve members of the Sanatan Sanstha and/or Hindu Janjagruti Samiti.

"On bare perusal of the chargesheet filed by ATS in the Nalasopara case, it has been categorically recorded that the objective of Sanatan Sanstha and its members is to terrorise the society at large and carry out terrorist activities, motivated by Kshatradharma Sadhna," the letter claimed.

It further said that the facts and circumstanced produced in the case show that there exists larger conspiracy and involvement of masters beyond the present accused.

"The investigating agency ought to have examined the officer bearers of Sanatan Sanstha whose involvement in larger conspiracy cannot be ruled out. From the use of psychiatric drugs on its members without their consent to planning and executing murders and bomb-blasts, it cannot be said that these conspiracies are possible with involvement of only members of Sanatan Sanstha," the letter stated.