From space, the fishing boats are just little white specks floating in a vast stretch of blue water off Papua New Guinea. But zoom in and there's the critical evidence: Two trawlers loading slave-caught seafood onto a massive refrigerated cargo ship.

The trawlers fled a slave island in Indonesia with captives of a brutal Southeast Asian trafficking ring whose catch reaches the United States. Hundreds of men were freed after they were discovered there earlier this year, but 34 boats loaded with workers left for new fishing grounds before help arrived — they remain missing.

After a four-month investigation, The Associated Press has found that at least some of them ended up in a narrow, dangerous strait nearly 1,000 miles away. The proof comes from accounts from recently returned slaves, satellite beacon tracking, government records, interviews with business insiders and fishing licenses. The location is also confirmed in images from space taken by one of the world's highest resolution satellite cameras, upon the AP's request.

The skippers have changed their ships' names and flags to evade authorities, but hiding is easy in the world's broad oceans. Traffickers operate with impunity across boundaries as fluid as the waters. Laws are few and hardly enforced. And depleted fish stocks have pushed boats farther out into seas that are seldom even glimpsed, let alone governed.

This lack of regulation means that even with the men located, bringing them to safety may prove elusive.

Officials from Papua New Guinea working with the International Organization for Migration said they were not aware of human trafficking cases in the area but are investigating. Numerous other agencies — including Interpol, the United Nations and the U.S. State and Defense departments — told the AP they don't have the authority to get involved.

A handful of former slaves who recently made it home to Myanmar said hundreds of men remain unaccounted for.

"Papua New Guinea can be a lawless place," said Lin Lin, one of the returnees, describing fishing in the poor island nation. "Fishermen could die anytime, but the captains would not care. If they die, they will just be thrown away."

He said he and his crewmembers still don't know why they were sent home last month, when their trawler returned to the same port in Thailand from which they were originally trafficked.

As the appetite for cheap fish worldwide grows, so does the demand for men who are paid little or nothing to catch it. Thailand's $7 billion annual seafood export industry is built on the backs of poor people from its own country and migrants from Myanmar, Cambodia and Laos who are sold, kidnapped and tricked onto trawlers.

In November, the AP found hundreds of such forced laborers on the remote island village of Benjina in eastern Indonesia — some in a cage, others on boats and more than 60 buried in a graveyard. To date, the reporting has prompted the rescue and repatriation of more than 800 men, many of whom said they were abused or witnessed others being beaten, or in some cases even killed.

Reporters followed the slave-caught fish back to Thailand and linked it to the supply chains of major U.S. food sellers, such as Wal-Mart, Sysco and Kroger, and American pet food companies, including Fancy Feast, Meow Mix and Iams. The businesses have all said they strongly condemn labor abuse and vowed to take steps to prevent it.

In April, a week after the AP story was published, the Indonesian government launched a criminal inquiry. It was already clamping down on illegal fishing nationwide with a moratorium on all foreign boats. Officials rescued hundreds on the spot but they discovered that a third of the company's 90 trawlers had already left — each with 15 to 20 migrants on board. The Indonesian government wants to bring the boats back for prosecution.

"They have to be responsible for what's happened," said Fisheries Minister Susi Pudjiastuti.

The disappearing act can start with a bucket of paint.

Kaung Htet Wai, 25, said his crewmates nailed a new name and number over the old one — Antasena 331 — and hoisted a different country's flag: the red, black and yellow of Papua New Guinea. Wai said his trawler did not dock for several months, and loaded many types of seafood, including mackerel, shrimp and shark, onto refrigerated cargo ships. Captains also repainted and renumbered other boats, and some kept flags from as many as four different countries in their hulls, according to former slaves and investigators.

The flag change protects rogue boats because typically the flagged states, not the host country, set their rules, said Mark Lagon, president of the Freedom House in Washington D.C. and former U.S. ambassador at large to combat human trafficking. Laws in general are weaker for fishing trawlers than other vessels, as is overall monitoring, he noted, creating a "black hole of governance."

As the boats hid, Indonesian investigators discovered that the company listed as their operator, Pusaka Benjina Resources, was really a venture between seafood industry tycoons and businessmen from Thailand and Indonesia.

Financial records going back seven years reveal Pusaka Benjina's lucrative business with a shipping company, Silver Sea Fishery Co. The trawlers crewed by slaves brought fish to Benjina, where it was loaded onto Silver Sea cargo ships heading for Thailand.

In a typical month, Silver Sea was invoiced about $500,000 for loads of seafood. One month the firm was billed $1.6 million, with a third of that charged to the Silver Sea 2 — the very same transport ship identified earlier this month in the satellite photo off Papua New Guinea.

Pusaka Benjina manager Hermanwir Martino, among seven people arrested on human trafficking charges, has said his company did nothing wrong. Silver Sea Fishery did not answer calls.

Photographs from the sky helped the AP actually catch the Silver Sea 2 in the act of doing business with the trawlers.

Over the past few months, satellite beacons show, Silver Sea cargo ships had been shuttling regularly between Thailand and Papua New Guinea. They slowed to a crawl or halted completely, apparently as they were being loaded with fish, in a crooked strait known as the dogleg.

Analysts at SkyTruth, a West Virginia remote sensing and digital mapping firm, identified the Silver Sea 2 by its signals. However, they warned that getting photographic evidence of it collecting fish from one of the trawlers that fled Benjina would be next to impossible.

Nonetheless, two weeks ago, DigitalGlobe, a Colorado-based commercial vendor of space imagery, maneuvered a satellite at the request of the AP toward coordinates of the Silver Sea 2, which had dropped anchor off Papua New Guinea. The cargo reefer struck experts as suspicious because it had turned off its locator beacon for almost two days, possibly while picking up seafood.

The satellite whizzed over Papua New Guinea at 17,000 mph, 380 miles up. Within a day, DigitalGlobe analysts spotted a high-resolution shot of a ship matching the Silver Sea 2 right down to the docking ropes and open cargo holds, with boats identical to those from Benjina nestled alongside, apparently offloading fish.

CEO Jeff Tarr said this was the first time the technology had been used to capture human trafficking live: "You can't hide from space."

Gisa Komangin, from Papua New Guinea's National Fisheries Authority, said that until now their focus has been on illegal fishing in the dogleg, and that a moratorium on all foreign fishing there is planned for the end of the month to crack down on poaching.

"When you are talking about illegal fishing," he said, "you are also talking about human smuggling."

The question now is if the men will be rescued. Many governments lack the resources — or the will — to implement a patchwork of outdated maritime rules, some written more than a century ago. Kenneth Kennedy, a senior policy adviser for the U.S. Department of Homeland Security, said international fishing agreements on sustainability, pollution and labor are needed, and those that do exist often go unenforced.

"If all these corporations, or ships, are ignoring these things put in place for the future of humanity, then what are we doing?" he asked. "We're just spinning our wheels."

Back in a dusty slum in Myanmar, relatives of the slaves still missing are desperate. One mother, Ohn Myint, went to the airport three times as men rescued from Benjina came home — hoping her 19-year-old son, Myo Ko Ko, would come out of the terminal. But every time, she left alone, a little more drained of hope.

"I am missing my son so much, each and every hour," she said. "I can only pray for him. I just think that only God can save him."

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McDowell reported from Yangon, Myanmar; Mendoza from Westminster, Colorado; and Mason from Tual, Indonesia. Esther Htusan contributed to this report from Yangon.

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Follow Mendoza, McDowell and Mason on Twitter: @mendozamartha, @robinmcdowell, @MargieMasonAP