One of India's best-known public health specialists and human rights activists, Dr Binayak Sen, has now spent a year in an Indian prison.
He is accused of links with Maoist rebels in Chhattisgarh, one of India's poorest states where the rebels have a strong presence. The doctor denies the charge.
During a court appearance earlier this year, Dr Sen said he did not support the Maoists.
"If they arrest people like me, human rights workers will have no locus standi. I have never condoned Maoist violence. It is an invalid and unsustainable movement," he told Tehelka magazine.
At the same time, Dr Sen has maintained the Maoists have tapped into a groundswell of legitimate grievances.
We also wish to express grave concern that Dr Sen appears to be incarcerated solely for peacefully exercising his fundamental human rights
Nobel laureates' letter
"The grievances [of the people] are real. There is an ongoing famine in the region. Forty per cent of the country lives with malnutrition," he said.
The Maoists say they are fighting their long-running insurgency for the rights of landless farmers and tribes.
Dr Sen, a trained paediatrician, was working with poor tribal people in Chhattisgarh, when he was detained last year. He was also a senior member of the local unit of a leading Indian human rights group, the People's Union for Civil Liberties.
He ran a weekly clinic for the local tribals and was piloting a community-based health programme in the state.
Rights groups, intellectuals and more than 2,000 doctors from all over the world have signed petitions demanding Dr Sen's release. They include prominent American writer Noam Chomsky.
The clamour for his release increased this week when 22 Nobel laureates joined the campaign and urged the Indian government to release the jailed activist.
Last month, Dr Sen was awarded the prestigious Jonathan Mann Award for Global Health and Human Rights for his services to poor and tribal communities and his unwavering commitment to civil liberties and human rights.
Dr Sen, 56, trained in medicine and paediatrics at India's prestigious Christian Medical College in Vellore and picked up a gold medal for his efforts.
Later specialising in social medicine and community health, he moved to Chhattisgarh in 1981, and began working with the leading mine workers' trade union leader, Shankar Guha Niyogi.
The two set up a hospital for mine workers after raising money from the community - the Shaheed Hospital in Dallirajhara is still cited as an example of a pioneering health initiative in India for the poor.
The doctor received a paltry salary of 600 rupees ($15) a month, and helped the facility grow from a small clinic to a 60-bed hospital in four years.
In the early 1990s, Dr Sen and his wife, Ilina, set up Rupantar, a non-governmental organisation training rural health workers, running mobile clinics and campaigns against alcohol abuse and violence against women.
Dr Sen's efforts in public health programmes, say local doctors, helped bringing down the infant mortality rate in the state and deaths caused by diarrhoea and dehydration.
Dr Sen has been outspoken about the ways the government is trying to tackle the Maoists in Chhattisgarh by backing a controversial civil militia of local tribals called Salwa Judum.
"The Salwa Judum," he said recently, "has created a dangerous split in the tribal community."
He has also expressed his deep concern over rising inequality in India despite the economic boom.
A poster demanding Dr Sen's release
Appeals for Dr Sen's release have poured in from all over the world
"We have to strive for more inclusive growth. You cannot create two categories of people," he told a journalist.
"There is a Malthusian process of exclusion going on in the country. Everybody must wake up to this, otherwise soon it will be too late."
His wife, Ilina, says the fight to release her husband goes beyond the man himself.
"I realise this goes beyond Binayak and my family. We are part of a much larger fight. We are struggling for the right to dissent peacefully. Our commitment to that gives me strength."