Dinh Thi Thanh was just 18 months old when she and her mother left Vietnam in 1989, hoping for a better life abroad.
Forsaking an unfaithful husband and their famine-threatened homeland, which was still recovering from decades of war, the mother and child boarded a Japan-bound ship in the Vietnamese port city of Hai Phong, costing them two bars of gold.
"My family on my dad's side had asked my mum to leave me behind because I was so young," Thanh, whose name has been changed for privacy reasons, told ABC News in a recent interview. "But she said if something's going to happen then we're going to be together."
The ship was packed with more than 100 other people, and there weren't enough food and supplies to go around. Thanh's mother, who spoke to ABC News on condition of anonymity, said they survived the voyage on the small amount of rice that she had brought with them.
But the boat never made it to Japan. It ended up shipwrecked on Hong Kong's shores after several days at sea. Everyone on board was arrested by Hong Kong police for illegal entry into what was at the time a British colony. Thanh and her mother were subsequently placed in a detention camp with scores of other migrants and refugees. They lived there for nearly two years.
"It was pretty much like a jail," Thanh recalled. "The people in charge basically took everyone's food, would only give out rations, and if they didn't like you they'd urinate in your bed or do just like really awful things."
A British immigration lawyer ultimately took on their case and won their freedom at trial. Thanh and her mother were able to move to the United Kingdom, where they were granted refugee status and settled in London. Both are now dual Vietnamese-British citizens. They live together in public housing and work at a Vietnamese-owned nail salon.
"We were lucky," said Thanh, now 32. "Life is good. I think we have it easy."
Thanh knows that many other Vietnamese migrants who embark on the 6,000-mile journey across Asia into Western Europe are not so lucky.
(MORE: Bodies of victims found in refrigerated truck in UK arrive in Vietnam)Back in October, 39 Vietnamese migrants were found dead in the refrigerated container of a tractor-trailer at an industrial park about 20 miles east of London. The container had been shipped from the Belgian port of Zeebrugge to Essex, England. The victims inside ranged in age from 15 to 44, and each appeared to have a bag with clothes, a mobile phone and other belongings, according to Essex police.
The driver of the vehicle, a 25-year-old man from Northern Ireland, was arrested and ultimately charged with 39 counts of manslaughter as well as one count each of conspiracy to traffic people, conspiracy to assist unlawful immigration, acquiring criminal property and transferring criminal property. He has pleaded guilty to conspiracy to assist unlawful immigration and acquiring criminal property. He has yet to plead to the other charges, police said.
At least two other men, also from Northern Ireland, have been arrested and charged in connection with the case. The investigation is ongoing, and police said they are searching for other suspects.
A large number of Vietnamese migrants began arriving in the United Kingdom by the 1980s, after the end of the Vietnam War and the reunification of North and South Vietnam in 1975. The number of Vietnamese-born people residing in the United Kingdom was estimated at 23,000 in 2018, according to the U.K. Office for National Statistics. However, there are other estimates that put that figure much higher, with tens of thousands believed to be undocumented.
Many Vietnamese migrants who are smuggled into Europe are extremely vulnerable to being trafficked along their journey as well as in the country of destination, oftentimes the United Kingdom, according to a 2019 research project by charities Anti-Slavery International, Every Child Protected Against Trafficking and Pacific Links Foundation.
Anti-Slavery International describes human trafficking on its website as “a process of enslaving people, coercing them into a situation with no way out and exploiting them.” People can be trafficked for many different types of exploitation such as forced labor, domestic servitude, forced marriage and forced prostitution, according to the group.
A 2017 report by the International Labor Organization and the Walk Free Foundation, in partnership with the International Organization for Migration, estimates that, on any given day in 2016, there were 40.3 million people worldwide who were forced to work against their will under threat or who were living in a forced marriage that they had not agreed to.
(MORE: How to identify human trafficking victims often 'hidden in plain sight')Many people leave their homeland on their own accord or willingly choose to be smuggled across international borders but can still become victims of trafficking as they are deceived and lured into situations of vulnerability and exploitation. Exploitation -- a fundamental characteristic of trafficking -- can occur at any point in a migrant's journey, but it's often only when they arrive in the destination country that they are forced to work in jobs or under conditions to which they did not agree, according to the 2019 research project by Anti-Slavery International, Every Child Protected Against Trafficking and Pacific Links Foundation.
Vietnam is continually featured in the top three nationalities of potential trafficking victims referred to the U.K. National Referral Mechanism (a government framework "for identifying and referring potential victims of modern slavery") as the number of Vietnamese victims has consistently increased over the past few years.
Nearly 7,000 potential victims of human trafficking and modern slavery from countries around the world were submitted to the National Referral Mechanism in 2018, a 36% increase from the previous year, according to an end-of-year summary.
And in the year through September 2019, more than 6,500 offences of modern slavery were recorded by police, a 53% increase compared with the previous year, according to the 2019 U.K. Annual Report on Modern Slavery.
The report notes that the sources of data “cannot provide a complete assessment of the actual prevalence of modern slavery, but they offer approximations for how the prevalence and reporting of modern slavery may be shifting over time.”
Many Vietnamese victims of trafficking are actually trafficked in their own country or just across the border in China, where Vietnamese girls are typically sold into brothels or as brides to Chinese men.
Dinh Thi Minh Chau, chief psychologist at the Blue Dragon Children's Foundation in Hanoi, which helps kids in crisis throughout Vietnam, has worked with some 800 human trafficking survivors over the years. But she said one girl's story is especially indelible.
The girl was unknowingly trafficked from Vietnam to China when she was 16, believing she would get a good job there, according to Chau. She was ultimately sold by her traffickers to a Chinese man who was intellectually disabled and couldn't find a willing bride in his own country. On the first day in the family's home in a remote mountainous province of China, the man raped the girl repeatedly as his mother held her down on the bed, Chau said.
Trapped and desperate to escape, the girl jumped out the window of the second-floor bedroom the following day. She survived the fall but fractured her spine. Due to the language barrier and the man's intellectual disabilities, he didn't take her to the hospital, according to Chau.
Chau said the man continued to rape her and that she "cannot communicate and she cannot move her body."
(MORE: Human-to-human transmission of new coronavirus reported in China)The girl lived in severe pain with the injury for a year, until she was finally allowed to contact her parents back in Vietnam because her husband's family was frustrated that she had not given them a child yet and wanted their money back. The girl's parents agreed to send money if they first took her to a hospital. The girl told the hospital staff about her situation and they contacted local authorities, who rescued her, according to Chau.
Blue Dragon helped reunite the girl with her family in Vietnam last year and she's been a patient of Chau's ever since. The girl, now 19, still cannot fully walk and has to use a wheelchair, so Blue Dragon is also supporting her with physical therapy.
"We are trying our best to get her legs stronger," Chau said. "It's very difficult for her."
While data indicates the trafficking of Vietnamese migrants to the United Kingdom may be on the rise, the official figures likely represent just a fraction of the actual number because many cases go unreported and known victims disappear, according to Dave Grimstead, co-founder and director of Locate International, a U.K.-based organization that helps families find missing people.
"How many others are out there that we just don't even know about?" Grimstead said in a recent interview with ABC News. "How many of those are still alive?"
(MORE: New lawsuit claims Jeffrey Epstein trafficked girls to US Virgin Islands as recently as 2018)For Grimstead, the number of missing children is particularly worrying. A report by charities Every Child Protected Against Trafficking and Missing People found that almost 20% of the total number of trafficked and unaccompanied children who were reported missing from the U.K. care system in 2017 -- 190 children -- had still not been found at the time of data collection a year later.
"These are the tip of the iceberg," said Grimstead, who was previously a police detective for the Avon and Somerset Constabulary. "They're things that the authorities know about. There are clearly going to be many more that are missing and not recovered."
The 2019 U.K. Annual Report on Modern Slavery notes that “traditional means of measuring crime (victimization surveys or police records) are less effective at measuring the prevalence of this complex and largely hidden crime whose victims are often too traumatized to report their exploitation or may not self-identify as victims.”
Those who leave Vietnam willingly in hopes of migrating to the United Kingdom without a visa typically pursue one of two routes offered by brokers or smugglers, who often make false promises of legal stays and well-paying jobs at the other end. The so-called grass route costs less -- about $3,000 to $5,000 -- but it can take months or even years to reach the destination country. Grass-route migrants usually travel overland from Vietnam into China into Russia by car and then into neighboring nations by foot, crossing through dense forests and over rugged mountains, according to the 2019 research project by Anti-Slavery International, Every Child Protected Against Trafficking and Pacific Links Foundation.
The so-called VIP route costs more -- ranging from $10,000 to $50,000 -- but is supposedly safer and takes less time to complete. VIP route migrants often go to China where they pick up recycled passports from traffickers before flying to Russia and then into Western Europe. But they will only be able to get so far as France or Belgium, despite assurances from traffickers, according to the 2019 research project by Anti-Slavery International, Every Child Protected Against Trafficking and Pacific Links Foundation.
Regardless of which route Vietnamese migrants choose, they have few options to get to their final destination beyond stowing away in shipping containers to cross the English Channel.
(MORE: 11 Chinese migrants found hiding inside furniture in moving truck at US-Mexico border)Chung Pham, a Vietnam specialist for Locate International, said the 39 Vietnamese nationals found dead in the refrigerated truck near London were likely a mix of VIP and grass-route migrants, based on information she said she received about the fees they had paid. Although Chung said she was "not surprised" by the incident, she admitted the scale of it "shocked" her.
"I came across this before," Pham told ABC News in a recent interview. "I knew that would happen to the Vietnamese illegal immigrants all the time."
Pham said refrigerated containers are typically used by smuggling and trafficking gangs because the thermal imaging equipment at the U.K. border, which would normally detect the body heat of stowaways, won't work on them. The driver turns up the freezer to sub-zero temperatures as the truck waits in line for inspection, according to Pham.
Based on open-source intelligence from the online Vietnamese community, Pham believes it's possible that the queue at the U.K. border was particularly long that fateful day in October and that the migrants' deaths may have been a tragic accident.
"Often, they (smugglers) calculate how long it will take to go through the border, and most of the time they are safe going through," Pham said. "But that time in particular, they (the online Vietnamese community) say it's just bad luck."
(MORE: Vietnamese police arrest 8 suspects in connection with grisly discovery of 39 bodies in tractor-trailer in UK)Pham said the networks of smugglers and traffickers bringing Vietnamese migrants to the United Kingdom are vast, well-entrenched and highly-organized, with people stationed at each of the stops along the way to the destination country. The United Nations Economic and Social Council recently estimated that smuggling networks from Vietnam are actively smuggling approximately 18,000 people a year to Europe.
Pham said only a handful of traffickers actually end up being prosecuted and getting jail time in the United Kingdom.
"A lot of cases are brought before the court and then dropped,” she told ABC News, noting that building a case against a trafficker is difficult for prosecutors and more investigative resources are needed.
“It’s not like [the police] are not doing their job,” she added, “but clearly the intelligence could be a lot better.”
When asked for comment, a spokesperson for the U.K. Home Office told ABC News, “Modern slavery and human trafficking are barbaric crimes and we remain committed to stamping them out. The Modern Slavery Act 2015 gives law enforcement the tools they need to tackle this, including a maximum life sentence for perpetrators.”
“Our significant reforms to the National Referral Mechanism for victims of modern slavery, such as the introduction of new Single Competent Authority and the launch of a digital referral form, ensure victims get the support they need more quickly,” the spokesperson added.
Many Vietnamese migrants who make it into the U.K. safely but still fall victim to trafficking are forced to work in cannabis production, at nail salons and in prostitution. Also, the salaries are often lower than promised. Traffickers will commonly confiscate the migrants' identification documents upon arrival and hold any debt they may owe over the heads as a means to coerce, control and exploit them, experts said.
Migrants or their families usually must borrow money in order to pay for the cost of the journey, and the deeds to their homes are typically taken as collateral. The burden of repayment lies heavily on the migrant's shoulders, which traffickers use to their advantage. Pham said that's why a number of Vietnamese migrants who are rescued from trafficking vanish from the system because oftentimes they actually go back.
"They feel they have the duty of going back to the trafficker to work for them in order to pay all the debt, so the house deed can be released back to the family," Pham told ABC News.
(MORE: Russia detains conman who built fake border with Finland to trick migrants)Still, the United Kingdom is considered a prime destination for many Vietnamese migrants. A 2014 survey sponsored by the British Embassy in Hanoi, which interviewed 346 Vietnamese who migrated illegally to the United Kingdom but had since returned, found that most returnees think of Britain as a "paradise," from the employment opportunities and income to the healthcare and legal systems, with even imprisonment being "enjoyable." There were various factors that motivated the returnees to migrate illegally to the United Kingdom, according to the survey; but two key ones were economic events, such as bad business, and occupations events, such as job loss.
"Possibly, this is the reason why the punishment was not hard enough to deter Vietnamese people from illegal migration and getting involved in illegal works in the U.K.," the report states, "which made them choose this as their destination for earning their living, rather than choosing other developed countries."
Thanh and her mother said they know of a number of Vietnamese migrants who came to the United Kingdom on student visas and never returned, or Vietnamese women who gave birth on U.K. soil so that their child got British citizenship. But they said they have never known of any situations of exploitation or forced labor.
"I think when they (migrants) get caught, because they don't have papers, they want to say that they've been kidnapped or trafficked over here, forced to work, so that they can sort of use that excuse to get asylum," Thanh told ABC News. "There probably are real cases out there where these things are happening, but we don't know anyone."
The case of the 39 Vietnamese migrants who died in the truck last October was "a tragedy," Thanh said.
"We've heard that a lot of people have gone that route," she added. "It was really surprising that that amount of people died."
Thanh, who has a bachelor's degree in psychology from Middlesex University London, said she and her mother are planning to open their own nail salon in the British capital soon. Although her mother wants to stay in London, Thanh hopes to save enough money to return to Vietnam one day and start her own business there, too.
"I think if you have the money, then Vietnam is a very good place to live," she said. "If I could open a store or something, or maybe a restaurant. The Vietnamese love to eat."