On the morning of 6 January, Boi Van Thang set out on a motorbike across the mountainous terrain of Chin state in western Myanmar. He would travel to a nearby village, he told his wife, and bring back meat for her and their seven children.

He never returned. Three days later his wife, Thida Htwe, received a call. Boi Van Thang’s body had been found. The bodies of eight other men and one boy had also been discovered.

Thida Htwe said that her husband’s throat was cut, that he had a knife wound in his chest and as well as several in his back, and that one of his legs was broken.

Photographs apparently from the scene, seen by the Observer, show a body that Thida Htwe identified as her husband. He is naked apart from his underwear, and his feet are tied. His clothes are in a pile beside his body.

Further images provided by Chin Human Rights Organisation (CHRO) show other victims of the massacre who were reportedly found nearby. In one photograph, five bodies are lying beside one another; some have their hands tied or material placed over their eyes or mouth. They have numerous wounds to their throats, chests and stomachs.

The youngest of those killed was 13. Chin journalist Pu Tui Dim was among the dead. He had been travelling with villagers, apparently on his way to visit family. He has been described as an “experienced ethnic media personnel who helped pave the way for independent news media in Chin state”.

Almost one year ago, Myanmar’s military ousted the democratically elected government of Aung San Suu Kyi and seized power in a coup. Since then, the country has descended into turmoil. The UN estimates the crisis will have driven almost half the population into poverty in 2022. Public services are barely functioning, as large numbers of teachers and medical staff are refusing to work in junta-controlled facilities, and instead operate their own networks.

The military has used violence and terror to stamp out dissent and silence opponents. Some 1,500 people have been killed by the military, and 11,800 arrested, according to a local human rights group. But opposition remains. As well as peaceful protest movements, local civilian defence forces have emerged, some of which are supported by established ethnic armed groups. The military has in turn launched artillery and air strikes.

In Chin state, where there is a strong resistance movement, as many as 80,000 people have been forced to flee their homes by fighting, according to the CHRO. Almost 900 were arrested between February and December last year alone, according to the group, while 182 people were killed during the same period. Some are thought to have been kidnapped and used as human shields.

“I have lived through the previous military regime and I read stories and reports from all over Chin state,” said veteran activist Salai Za Uk Ling of the CHRO. “I have never seen this level of brutality in my life.”

In December, more than 30 people, including children, were killed in Kayah state on Christmas Eve. Their bodies were found burned beyond recognition. Earlier in the month, the military rounded up and killed 11 people in the Sagaing region of Myanmar’s north-west. The group was shot and then set on fire, according to local media reports.

Alongside such massacres, the military has increasingly deployed a scorched earth campaign as part of its intensifying reign of terror. Myanmar Witness, which collects evidence of military abuses, has corroborated 57 incidents where buildings in villages and other civilian areas have been set alight. Many have been attributed to the military. Extensive damage has been recorded within Thantlang, in northwest Chin state.

Such violence was reminiscent of the Rohingya crackdown in Rakhine state in 2017, said Aung Myo Min, human rights minister of the National Unity Government (NUG), the administration in exile. “They sent more troops, they went village to village and torched all the houses, and forced the massive displacement to other areas,” he said. “It’s the same pattern.”

The NUG is investigating the killing of Boi Van Thang and other civilians murdered that day. It will submit its findings to a group established by the UN Human Rights Council to collect evidence of violations of international law committed in Myanmar.

“It is important for us to bring justice and make sure the culture of impunity is no longer in the future of Myanmar,” said Aung Myo Min.

Activists suspect the junta has targeted Chin state because it wrongly believes local resistance can easily be silenced. “They always have this perception that the people of Chin state are weak and can be easily subjugated,” said Salai Za Uk Ling.

The state, in western Myanmar, is the nation’s poorest, and home to the Chin people, a mostly Christian ethnic minority that has long suffered oppression in the Buddhist-majority country. Churches are among the buildings that have been torched.

Activists say the military’s assumption that it could impose order in Chin state have been wildly inaccurate. According to CHRO, close to 80% of its civil servants are refusing to work after joining the civil disobedience movement. “The administrative apparatus no longer functions in Chin state apart from in towns or capitals like Hakha,” said Salai Za Uk Ling.

Tuesday marks the first anniversary of the military’s seizure of power in Myanmar, he said, but added: “The coup has not succeeded yet.” In some villages, most young people had joined the armed resistance, he said.

The murder of Boi Van Thang and others on 6 January has prompted a fresh wave of people from villages near to Matupi, a strategic crossroads in Chin state, to flee their homes.

El Zamoon was among those who fled. He spent eight days travelling, mostly by foot, across steep roads to seek safety across the border in India’s Mizoram state. Children, exhausted, fell from their bikes along the journey.

El Zamoon fled when the military began firing heavy artillery at his village. “Everyone here wants to go back to their homes, but they are afraid of the soldiers,” he said.

Families of those killed left without the opportunity to hold a ceremony for their loved ones.

Thida Htwe was unable to see her husband’s body or hold a memorial. She said he was a kind-hearted man who, in his spare time, would tutor village children. “He was only 38 and a good father to our kids,” she said.

“Now I am left with seven kids. I don’t know how to raise them without him,” she said. When she sees other families she feels a deep sadness. “I wish he were here with us. We will never forget him.”