When David and Ally first saw Marcus, they knew he was destined to be their son.

“For me it was love at first sight,” said David. Their long adoption journey had come to an end. Months later, the baby from Indonesia was in their arms and the family was ready to start their life together.

But now, years later, they face the possibility of losing Marcus because he is believed to have been trafficked into Singapore.

He is one of at least 20 babies alleged to have been illegally bought in Indonesia for adoption in Singapore in recent years. Nearly two dozen people have been arrested for alleged human trafficking last year and are now on trial in West Java.

This means authorities may have to decide if Marcus and other children, who would by now have spent most of their lives in Singapore, should stay with their adoptive parents or return to their biological parents in Indonesia.

Both countries have yet to state what will happen to the children. For David and Ally, these last few months have been agonising.

The high-profile case has highlighted the enduring problem of child trafficking in Indonesia, fuelled by parents who sell their children.

It has also raised questions over how Singapore – known for its tight controls and meticulous checks – failed to detect the alleged trafficking and even approved some of the adoptions.

David and Ally agreed to share their story with the BBC on condition we use pseudonyms, as they fear jeopardising their chance to keep Marcus.

“The anxiety is always there, at the back of our minds,” said David.

“There’s always the thought that Marcus might be taken away.”

David and Ally had always wanted children but after Ally went through several painful miscarriages, they decided to adopt.

But they faced a long wait for a Singaporean child – with one adoption agency giving them a queue number of 142.

So they did what many Singaporeans in this situation do, and looked overseas. An estimated two-thirds of the children adopted in Singapore every year were born elsewhere, usually in neighbouring countries.

David and Ally chose a local agency that specialised in arranging adoptions of Indonesian babies.

Weeks later, they were peering at a tiny infant held up to the camera, in a video call arranged by the agency.

“What was so special about him that caught our attention? He’s very smart ! He smiled at us,” recalled David.

The couple paid tens of thousands of dollars, a sum they were told would cover agency fees, legal costs, expenses for the child, and a “token sum” for the biological parents.

Within a few months, Marcus was brought over to Singapore. The moment he was placed in their arms, “we felt nervous, scared, but happy,” said David. “We looked at each other and we said…”

“This is it, this is the real deal,” Ally finished his sentence.

Marcus’s adoption in Singapore was approved swiftly, and the final step was to apply for his citizenship. When immigration officials called them in for a meeting, they were expecting good news.

Instead, their lives were upended. They were told the citizenship application was suspended and that Marcus had possibly been trafficked into Singapore.

“That’s when I burst,” said David, who felt the Singaporean government should have done more in their checks.

“I said to them: ‘Didn’t you do your due diligence? You did all the checks, right? You put us through a tough but necessary process, that is why we abided to it’. They could not answer us.”

David and Ally say the possibility that Marcus could have been trafficked never once crossed their minds.

They said they tried their best to do their own background checks but were limited in their lack of knowledge. It was, after all, the first time they had ever adopted a child.

The couple argue that the onus is on the Singapore government, given that its officials had done thorough checks on them during the approval process for Marcus’s adoption.

“The [officials] are the experts on this, to see whether this is legitimate. They deal with so many adoptions, day in day out. Not us,” said Ally.

The MSF declined to answer the BBC’s questions on whether it did any checks on the babies who entered Singapore and how it usually conducts checks on the adoptions of foreign children.

It pointed to previous statements saying it was providing support to the affected parents and there were “some delays” in processing citizenship applications for their children.

The ministry has also promised to conduct a review of adoption processes.

In Indonesia, this case is one of at least seven suspected baby trafficking syndicates investigated by authorities in the last few years. One of these syndicates that operated out of Yogyakarta allegedly handled at least 66 babies.

Official figures show the number of trafficked young children nearly tripled between 2021 and 2024, from 27 to 70 children. These only account for cases they have tracked, with the actual number likely to be much higher.

While some parents were allegedly coerced by traffickers into selling their babies, others were willing to do so because they could not afford to raise their children or needed money.

During the West Java trial, a witness named Dani Hidayat said he was bankrupt and jobless when his wife was about to give birth to their fifth child, and their “financial and economic situation was not ready”.

Hidayat joined a Facebook group for adoptions, and was approached by a woman claiming she could not have children. They agreed she could adopt his baby once the child was born.

The woman gave Hidayat five million rupiah ($290; £214) and promised him two million more. Hidayat said he needed the money for his wife’s recovery.

The woman is alleged to be a broker for the trafficking ring – and it was Hidayat who ended up exposing them.

When he failed to receive his second payment, he went to the police alleging his son was abducted. Police caught the woman and, upon inspecting her phone, found she had procured dozens more babies for adoption in Singapore and Indonesia.

Hidayat’s son was eventually located and is currently in the care of social services. The child was not one of the 20 babies bound for Singapore.

The BBC has asked Indonesian police whether the biological parents of the allegedly trafficked babies would be investigated. We are yet to receive a response.