Arupjyoti Saikia is a professor of history at IIT-Guwahati
As many as 42 scholars and academicians, including noted historian Ramachandra Guha, wrote to the NIA yesterday in support of IIT-Guwahati professor Arupjyoti Saikia, after he was summoned and questioned for hours as a witness in connection with a case against farmers' rights activist Akhil Gogoi; Mr Gogoi and his aides, who have been in judicial custody for over a month, are accused of helping Maoists set up a base in Assam under the cover of anti-CAA protests.
The NIA has yet to explain why Mr Saikia was questioned. However, his legal counsel, Shantanu Borthakur, has said he was called to "give witness". Mr Saikia is being questioned again today.
In their statement the scholars asked the NIA to "treat him with dignity... and allow him to continue his work unimpeded".
"Professor Saikia is an adornment to the literary and intellectual world of Assam and of India. He is also an individual of high moral character; gentle, soft-spoken, and utterly non-violent. His devotion to his students at IIT Guwahati is exemplary," the statement said.
"That a scholar of such standing, and a human being of such decency, has been called for intensive grilling by the NIA is deeply distressing. We urge that the NIA treat him with the dignity and respect he deserves, and allow him to continue his professional work unimpeded," the statement added.
Responding to the letter, the Congress's Jairam Ramesh said he 'was "absolutely shocked and dumbfounded by Arupjyoti's ordeal".
"I am absolutely shocked and dumbfounded by Arupjyoti's ordeal. He is one of our most outstanding historians and his most recent book on the Brahmaputra is a classic. I wholeheartedly endorse the appeal made by these distinguished scholars," Mr Ramesh tweeted, attaching the scholars' statement.'
On Saturday Arupjyoti Saikia, 52, a professor of history in IIT-Guwahati's Department of Humanities and Social Sciences, was called to the National Investigation Agency's in Sonapur, on the outskirts of the city.
Mr Saikia was reportedly grilled over telephone calls to activists allegedly helping Maoists under the cover of protests against the Citizenship Amendment Act, or CAA.
Last month Assam minister Himanta Biswa Sarma, a key North East BJP leader, suggested a central government organisation employee was directly involved in anti-CAA protests.
According to a report by NE Now News, a local media organisation, Mr Sarma also said electronic evidence linked a leading Assam academician to a plot to burn down the Assam Secretariat at the Dispur capital complex.
The contentious CAA, pushed through parliament in December, makes religion the test of citizenship for the first time. The government says the law helps non-Muslim refugees fleeing religious persecution from Muslim-dominated neighbouring countries, but critics say the law violates the Constitution's secular tenets and discriminates against Muslims.
Activists in Assam, where protests broke out even as the law was being debated in parliament, also feel the CAA will lead to an influx of Bangladeshi refugees and endanger local identities and jobs.
The protests have been widespread and sustained; in Assam at least five people died in December, leading to the Army being called out, a curfew imposed in Guwahati and suspension of internet services.