The violence used by Myanmar's armed forces against unarmed opponents since the coup in February has shocked the world; more than 800 people have been killed, most by military gunfire. But the deaths in custody of two officials from the National League of Democracy - the party led by Aung San Suu Kyi - have cast an even grimmer light on the military's actions.

On Saturday, 6 March, cities across Myanmar were on edge.

Three days earlier they had experienced what had then been the most violent day since the coup in February - with the UN recording the deaths of 38 people.

The army had seized power on 1 February, after claiming - without evidence - that a previous election which saw the NLD gain power was fraudulent.

Ms Suu Kyi and senior leaders were put under house arrest - triggering waves of protest against the military.

For the first three weeks the military had seemed unsure how to respond to the protests.

But by the end of February they were using increasing levels of lethal force. By the first week of March, it was clear there would be no restraint.

The historic downtown neighbourhood of Pabedan in central Yangon, with its narrow alleys between crumbling colonial buildings, had seen plenty of drama.

That week, activists had built barricades in some streets to keep out the security forces, and there had been several clashes.

Pabedan has a diverse population, with a large number of Muslim residents and eight mosques in the township.

In last year's general election, Sithu Maung, one of only two Muslim candidates fielded by NLD won the parliamentary seat there.

His campaign manager was Khin Maung Latt, a veteran NLD activist who had moved to Pabedan many years before and lived with the family of a Buddhist lawyer.

He co-owned a tour company, had run a video rental shop, and had been active in the NLD since 1988, becoming the chairman of his local branch. He was a well-known and well-liked member of the community.

"He was very religious and prayed five times a day," Sithu Muang told the BBC from where he is now hiding from the military.

"But people from all faiths loved him. He did a lot for the community, like making new green spaces for children to play in. He was very important to the NLD."

An unknown cause of death

Khin Maung Latt was at home with his adopted family when police and soldiers arrived shortly after 21:00 local time (14:30 GMT).

The soldiers were identified by neighbours as members of the 77th Light Infantry Division, a unit notorious for human rights abuses.

According to Ko Tun Kyi, a friend of Khin Maung Latt, the soldiers were actually looking for U Maung Maung, a lawyer who was more senior in the NLD and who had already gone into hiding.

Instead, they broke into Khin Maung Latt's home, he says, and dragged him out, kicking and hitting him.

Ko Tun Kyi believes Khin Maung Latt was then taken to Yangon City Hall, one of the first buildings to be commandeered after the coup.

Early the next morning, Khin Maung Latt's family received a phone call from police telling them to come and collect his body from a military hospital in northern Yangon.

They were told there that he had fainted, and that they should inform people he had suffered a heart attack.

But the family insists that the 58-year-old was in good health and had no known illnesses. They say his body showed signs of multiple wounds on it, and was covered in a blood-soaked cloth.

The body had been cut open and then sewn up in what may have been an autopsy, but the family has been given no official report on the cause of death. He was buried later that day in a Muslim ceremony.

The US-based human rights organisation Physicians for Human Rights has examined the evidence, including photographs of Khin Maung Latt's body.

While it is unable to make any definitive judgements, it has concluded that the cause of death given by the military authorities is implausible, and that he is most likely to have died from "homicidal violence" while in custody.

Ko Tun Kyi believes he was deliberately killed. He was detained less than ten hours before his family was informed of his death; it was not the result of prolonged torture.

"I was once jailed and interrogated, so I know how they get information out of you. Maybe they believed he was connected to the Committee Representing the Pyidaungsu Hluttaw (CRPH) - the rival government supported by the opposition," he said.

"Maybe they were trying to get information about what the NLD is planning, or where activists were hiding?"

He believes it was Khin Maung Latt's prominence in the local NLD that made him a target of military retribution, although he was not an obvious threat to the military junta.

'His intestines had come out'

But the theory that the military was targeting Aung San Suu Kyi's party was given more weight two days later, by the death of another NLD official, Zaw Myat Lynn.

He was far more prominent in the opposition movement than Khin Maung Latt - and his treatment appears to have been a lot more brutal.

Zaw Myat Lynn was the 46-year-old director of a new vocational college in the industrial district of Shwe Pyi Thar - one of several opened under the NLD government.

He was also a dedicated NLD activist, and right after the coup he was chosen to be the local representative of the CRPH.

In the days before he was captured, he posted stirring messages on his Facebook page, calling on the residents to keep up their revolutionary struggle against the military, who he referred to as "dogs" and "terrorists".

"Zaw Myat Lynn was a political powerhouse," an NLD official from the same township, who is now in hiding and cannot be named, told the BBC.

"He was a superb speaker. He was the only person from our township who was able to unite people and lead the post-coup demonstrations. He was the one who persuaded employees from various government offices to join the civil disobedience movement."

The official remembers joining him and his students at a protest on 8 March.

"He didn't appear to be worried in the least," he says. "He even offered to have me stay with him at his school, claiming that it was too dangerous for me to be outside on the streets."

That evening Zaw Myat Lynn returned to the college with some of his students. Shortly before 02:00, soldiers broke through the gate of the college.

The students told their teacher to escape by climbing over the back wall. Seven of them were arrested; at the time no-one was sure what had happened to Zaw Myat Lynn.

At 15:00, his wife, Daw Phyu Phyu Win, received a call from a local official in Shwe Pyi Thar telling her that her husband was dead, and that she could see his body - which was at the same military hospital where Khin Maung Latt's family had been.

They found him badly bruised. His belly had been cut open by a long, horizontal incision, and she said his intestines had come out.

She was shown a large wound in his back. The official state media reported that he had fallen backwards onto two inches of steel pipe while climbing out of the back of his school. It warned that severe action would be taken against anyone giving alternative accounts of his death.

The Physicians for Human Rights doctor who examined photographs of the corpse concluded that the official explanation lacked credibility.

The horizontal cut across the belly was inconsistent with any autopsy incision, he said. The torso had also been cut vertically for what may have been an autopsy. The massive bruising on both sides of Zaw Myat Lynn's torso was also inconsistent with the official account that he had fallen while escaping.

These injuries were much more likely to have been inflicted on him by his captors. The PHR doctor could draw no definite conclusions from the hideous injuries to his head.

Zaw Myat Lynn's face was badly disfigured by the time of his funeral. However, the PHR doctor believes this may be due to decomposition.

The military authorities would not allow his wife to take the body until the day of his funeral, and it took her three days to arrange it. The body appears to have been left unrefrigerated.

It is hard to know why these two officials were subjected to such terrible torture, which from all the evidence appears to be what killed them.

The military junta has said little to justify its brutal treatment of those who oppose its coup.

The BBC has asked the spokesman for the junta to respond to the PHR report, but at the time of publication had not received one.

A brutal track record

The military has a track record of treating victims in Myanmar in ways that suggests that they were unlawfully killed.

Bodies are dragged away from the scene in military trucks - usually no attempt is made to give first aid to those who might still be alive.

Some families have been blocked from recovering the bodies of relatives, which are cremated by the military authorities with no sign of an investigation into how they died.

Most bodies are returned with signs of torture and extensive autopsy work, but no credible or independent report provided to explain how they died.

The Association to Assist Political Prisoners in Burma, which has for many years documented abuses by the security forces, identifies 75 people missing from the turmoil following the coup, with 23 of those confirmed as disappeared, presumed dead.

Brutality and unaccountability have always been problems in the treatment of dissidents by the authorities in Myanmar; but they have become far worse since the coup.

In this case, neither man was a significant figure in national politics.

It is possible that the decision to treat them that way was made solely by the military units which detained them, perhaps inflamed by local or personal grievances, perhaps just in the heat of the moment. An instilled hatred of politicians might also have been a factor.

Myanmar's security forces have been habitually violent in their treatment of detainees for decades, and very rarely held to account.

But the NLD official believes Zaw Myat Lynn was killed in this way to send a message.

"I believe they reasoned that by executing [him] in such a terrible manner, they would instil fear in the people, causing them to retreat."