It’s been a year since Chantal buried her eight-year-old son. “I lost my mind that day,” says the 46-year-old, wiping tears from her cheeks.

Curled on the porch outside her small house in the Democratic Republic of the Congo’s eastern town of Goma, Chantal says she’ll never forget the day when a man, wearing a hat that covered his face, delivered a letter saying that her son Charles had been kidnapped.

“They told me if I ever wanted to see my son again I had to call this number,” the mother of eight recalls.

Over the course of a week, the family was told to send varying amounts of money directly to the kidnappers if they wanted to see Charles again.

“That week was so devastating, thinking about how he was doing and the conditions he was living in,” she says. Helped by friends and neighbours, Chantal and her husband cobbled together roughly $1,000 (£755), which they sent to the kidnappers in small amounts using mobile cash transfers.

But seven days after Charles was abducted, his decapitated body was found dumped in a nearby neighbourhood.

Over the past three years, there have been a growing number of kidnaps in Congo’s conflict-ridden Kivu provinces.

People are even abducting themselves and getting a friend to say they've been kidnapped, to get money Mutete Mwenyemauli

More than 730 people in North and South Kivu have been abducted or kidnapped for ransom since the beginning of the year, according to the Kivu Security Tracker, a joint project between Human Rights Watch and the Congo Research Group that has tracked the number of kidnappings since April last year.

But the kidnapping of children for ransom is a relatively new phenomenon, particularly in Goma, the capital of North Kivu. Exact figures are hard to come by, but one child protection group in North Kivu says that, in 2017, 215 children were abducted in the province and 34 killed. Between January and June this year, 97 children have been abducted and 21 killed.

It is unclear who is responsible, but authorities say conflict, high unemployment and the country’s dire political situation are driving people to desperate extremes. Meanwhile, international humanitarian groups are withdrawing from the area amid security fears, taking local jobs with them.

“People are even abducting themselves, getting friends to call family members to pretend they’ve been kidnapped so they can get money,” says Mutete Mwenyemauli, chief administrator for Goma’s Himbi district. The number of abductions in his neighbourhood has already reached 10 this year, the same number there were in all of 2017, he says. In April, three boys from the same family were kidnapped and killed.

“People have given up and are asking what they can do to survive. They’re looking for other ways to make a living,” says resident Fiston Materanya, 30, who hasn’t had a job in five years. Materanya says a lack of alternatives has persuaded many of his unemployed friends to join armed groups.

He has heard that other young men in the area have resorted to kidnapping.

The kidnappers are understood to be men, mostly, although some women are involved. “People realised there’s money to be made through kidnapping,” says a Goma-based international researcher, who did not want to be named. “I don’t know for sure why children are being targeted, but I reason that children are comparatively more gullible, less resistant and their kidnapping evokes greater panic in loved ones.”

Jean Claude Buuma Mishiki, a researcher at the National Youth Reflection Circle, blames Congo’s broken justice system. “This is a problem that is happening in many parts of the country and the phenomenon is spreading fast because impunity reigns everywhere,” he says.

Children in Kivu, Congo, where one child protection group says 215 children were abducted and 34 killed in the province in 2017. Photograph: Sam Mednick

In June last year, Goma resident Bridgette Ndoola received a call from an unknown number two hours after dropping her son, eight-year-old Josefat, at school.

“They asked me if I’d heard about kids who had recently been abducted and killed,” says the 30-year-old, clasping her hands. The man on the phone told Ndoola that he had kidnapped her son and wanted $6,000 for his release.

A single mother of five with no job, Ndoola didn’t have any money. During a subsequent call with the abductors they put Josefat on the phone, beating him and forcing Ndoola to listen to his screams. They told her it would be the last time she would ever speak to her son.

“He was crying and saying ‘Mum, please give money or they’ll kill me,’” she says.

With help from the community, Ndoola transferred more than $1,000 to her son’s captors. Six days after he was taken, Josefat was released. But his condition was critical. He had been stabbed several times in the chest, his ears were cut and five of his teeth had been pulled out.

Goma’s mayor, Timothée Muyisa, says the city has launched an investigation aimed at uncovering “who these men really are”. But residents remain wary of local authorities, believing they may be complicit. Josefat says one of his captors was a neighbour, but Ndoola has been too afraid to report him. “Many police collaborate with the abductors,” she says.

Jean-Paul Lumbulumbu, a prominent lawyer in the region, says kidnapping has existed in this part of the country for years, albeit it was once less prevalent. “There were rare cases,” he says. “But since 2014, the phenomenon has amplified and become a phenomenon of society, a means of easy gain of money.”

Lumbulumbu believes it can be stopped if the authorities act. As well as adopting a zero-tolerance policy on kidnapping, he says the government must compel mobile companies to establish geolocation software so that kidnappers can be found and stopped.

“The majority of cases of kidnapping prove to have a purely financial motivation. It is possible to put an end to it and we have proposed solutions to the authorities,” he says.

Josefat has now switched schools, attending one closer to home. Seated on the couch in his living room, the young boy smiles as he fiddles with a piece of string. “I like school because I’m free and happy there,” he says. “But sometimes I have bad dreams.”

Ndoola doesn’t like to talk to Josefat about the kidnapping because, she says, he finds it difficult to cope with the memories. Helped only by family and friends, he has not received any psycho-social support from aid groups in the area.

While she is happy to have him back, Ndoola worries it could happen again. She pulls out a plastic bag full of bloodstained clothes. “This is what he was wearing when he was taken,” she says. “It makes me sad, but I keep them to remember what happened.”