A Catholic nun named Valsa John was murdered the Indian state of Jharkhand on Tuesday.

John, who is from the state of Kerala in the deep south, was killed by unidentified assailants who broke into her home at 2 a.m. in the city of Pachwara village. Reports on the cause of death vary, with some Indian news sources saying she was shot and others suggesting that she was hacked to death.

While the local church has stated that the circumstances surrounding the nun's murder are unclear, many are calling it a retribution killing done by the so-called mining-mafia, or coal-mafia.

John worked with tribal communities in Jharkhand, particularly the Santhal tribe. Indigenous tribes-people in India are often exploited and intimidated by mining corporations that want their land.

There are 32 different tribal groups in Jharkhand who make up about 28 percent of the population. Their lifestyles range from the traditional and isolated to the  modernized, while some are still classified as hunter-gatherers.

The mining-mafias are thought to control every aspect of the industry in Bihar and Kerala states. The mobs fix prices, control shipping routes and make deals with local politicians and police officials, making it easy to set-up mines illegally on protected land.

Nine platoons of policemen came in vehicles and took positions at the construction site to counter any protest by the tribal people, an article titled India's New War: Mining Mafia vs Oppressed Tribals said, detailing a 2006 protest in Orissa state that eventually turned into a battle between police and tribesmen.

Some policemen, armed with semi-automatic rifles, surrounded the site. With the obvious intention to shoot to kill; the top officers who have the authority to give the order to fire were present from the very start. The Executive magistrate, the District Superintendent of Police and the Collector were all present.

Sister Valsa was allegedly threatened by the mafia in the past for protesting against a coal mine being built on tribal land.

She was pursuing a course in LLB (Bachelor of Laws degree). Her life was under constant threat and she had communicated it to Jharkhand political leaders like Shibu Soren and Stephen Marandi, her brother M. J. Baby told the Times of India.

She had mentioned about certain threats, but we never thought that the mafia would finish her off.

There are allegedly a number of different mafia raj, or industry-based criminal gangs, controlling sectors like contracting, logging and real estate development.

John belonged to the Sisters of Charity of Jesus and Mary religious order. Kerala has a relatively large Christian population. She will be buried on Thursday.

She always wanted to work for the welfare of the downtrodden and the poor, Baby added.

Around 19 percent of people in Kerala practice Christianity, a significant figure compared to the 2.3 percent nationwide. About four percent of people in Jharkhand are Christians.