“Then they stepped on her and tore her apart. Her remains were scattered on a trail about 800 metres long,” he said.

Zhao was the fourth person killed by the same group of Asian elephants in Fazhanhe in less than three years. The youngest victim was a child, killed on a road at night, according to local villagers.

The elephant group first visited the prefecture in 2014, local forestry authorities said. At the time, it contained 13 elephants. But since then, the group’s numbers have swollen nearly 50 per cent to 19 elephants, according to Yang Zhengqiang, the prefecture’s forestry director.

Zhao’s violent death stoked panic among locals and deepened a fear that the elephants were on a rampage against humans. Some residents burned tires at their front doors after nightfall to keep the elephants away with fire and smoke.

Zhong Shuangfu, a farmer in nearby Liangzilaozhai village, told the media that some fearful villagers dared not to talk openly about the elephants.

“They are listening and they can understand human talk,” he told btimes.com, a Beijing-based news website. “We dared not to say bad things about them because they will come to us for revenge.”

Elephant accidents have happened regularly for years in Yunnan, a province in southwestern China with large areas of tropical forest. In the past, elephants have attacked farms, solar power plants and even vehicles on roads.

More than 40 people died in these accidents from 1991 to last year, as the wild elephant population doubled to more than 300 in less than a decade, according to a provincial government estimate.

But experts argue there is little the authorities can do to manage the issue.

“We cannot hurt elephants because they are protected by law,” said Jiang Xuelong, who studied wild elephants at the Kunming Institute of Zoology, Chinese Academy of Sciences. “We cannot ask the farmers to leave either, because they have been living in the village for many generations.

“So far, there is not an effective method to solve the dilemma.”

Official explanations for casualties include accidental encounters gone awry, elephants foraging for food clashing with human activity, the rapid expansion of towns and cities, burgeoning agricultural activity and motorways extending deeper and deeper into forests cutting through natural elephant habitats.

But even some government officials have wondered whether the elephants are now deliberately hurting humans.

Zhou Yunhua, deputy director of Menghai county’s forestry bureau, told mainland media in 2015 that he was personally hunted down by wild elephants twice in the woods.

“When an elephant kills, it does not come [at you] like thunder, as the outside world imagines, but like an assassin, quiet and invisible,” he told jiemian.com, a news website run by Shanghai Daily. “When you see them, it’s too late.”

Zhou said he survived the onslaught only because some of his companions were policemen with guns.

While the villagers’ suspicions about “vengeful elephants” sound far-fetched, an animal behaviour scientist said their fears might not be entirely groundless, given the string of fatal attacks by the same group of elephants in Fazhanhe.

“Scattering remains for hundreds of metres apart is not quite normal. It could be ritual,” said the Beijing-based government researcher, who asked not to be named because of the issue’s sensitivity.

“They might be doing this for something bad that had happened to them or other members in their family. Elephants are known for their long memory,” the researcher said.

Studies have shown that an elephant’s brain is not just larger than a human’s, but denser with many folds in the temporal lobe, allowing it to store more information. Some researchers have found that elephants mourn deceased family members, and can even suffer human-like mental shocks similar to post-traumatic stress disorder.

In a study published in 2013, researchers with the University of Sussex in Britain found that elephant calves that lost their parents in a massive culling campaign in South Africa were still haunted by grief decades later, and being in that state impaired their decision-making ability.

Elephants in the Fazhanhe region have felt the brunt of human violence recently.

A pregnant elephant was shot and killed by a farmer in Guanping, a village about 70 kilometres east of Fazhanhe, in 2015. The mother elephant died with a home-made bullet in her head. In her womb was a fully developed fetus, according toXinhua.

The farmer said he was trying to protect his family as the elephants approached his house. He was arrested for illegal possessing firearms.

In 2014, an elephant was found dead in the same region with its tusks missing. It was killed by poachers, forestry authorities told local media.

But Jiang Xuelong, the wild elephant expert with the Kunming Institute of Zoology, said it was too early to attribute the attacks at Fazhanhe to attempts at retaliation against humans.

While the attacks are “puzzling”, so far there is no evidence to suggest the elephant family had been hurt before by humans, Jiang said.

“Why elephants attack humans still remains a myth in science. Many reasons have been speculated, but so far none is backed by solid scientific evidence,” he said.

Local forestry officials told btimes.com that many natural forests in the area had recently been converted to rubber tree plantations. Humans encroached on the elephants’ living space, which increased the chance of conflict.