Amid the biggest wave of migration to Europe in decades, fast-growing smuggling networks are spiriting Syrians and others to the continent, law enforcement officials say — and there are few limits to the sophistication of their efforts.

The 71 corpses discovered in a truck on an Austrian roadside last week are only a grim glimpse of a fast-expanding wave of human smuggling seizing Europe, said officials who are charged with hunting the smugglers. Vans that once may have been used to smuggle cigarettes are being used for the much more fragile cargo of humans. On social networks and in person, migrants can pick from a menu of services, ranging from a slippery seat on a rubber dinghy to Greece all the way to a chartered business jet straight to the refugee haven of Sweden.

The long trek across the Western Balkans has taken fresh prominence in recent months after years in which Syrians and Iraqis fleeing war favored a perilous sea route from Libya. Now thousands of migrants set out every day to make the long journey from refugee camps neighboring Syria to the Western European nations that have offered them safe harbor. They do so hand-in-hand with smugglers, who often advertise their services openly on Facebook and other social media sites.

“There is a growing number of networks that we saw in the past were dealing in the trafficking of illegal drugs and are now shifting to people smuggling,” said Robert Črepinko, the head of the organized crime unit at Europol, the European Union’s policing arm. “The number of criminal activities is growing with the same speed as the number of illegal migrants.”

The criminal boom has been so rapid that Europol’s new online monitoring unit, which on July 1 began monitoring terrorist-related social media activity, has recently expanded to monitor smuggling, Črepinko said.

National law enforcement authorities have struggled to keep up with the influx of migrants, as old criminal rings move into new areas of business.

“As a global criminal enterprise, it is very lucrative,” said Patrik Engström, the head of the Swedish police’s national border policing section, who has monitored human smuggling and trafficking for years, and watched as it has taken new life in Europe since the beginning of 2014.

Sweden, along with Germany, has become Europe’s top destination for asylum-seekers after the government announced that Syrian refugees would be granted permanent residency and the right to resettle their entire families within the country’s peaceful borders.

A trip at all costs

Engström said his agency has uncovered schemes to get to Sweden that are as basic as an RV over a bridge and as complicated as a chartered plane that lifted off from Turkey, charging the Syrian passengers about $10,000 each for the privilege. When they landed, they claimed asylum, he said.

The wide range of methods reflects the diverse circumstances from which the asylum-seekers are coming. Syria’s conflict, well into its fifth year, has upended the lives of many middle-class families with deep wells of savings. Many of them might have stayed close to Syria for years in the hopes of returning home before giving up and turning toward Europe.

Asylum-seekers have powerful motivations to make it to wealthy nations such as Germany and Sweden without being detected along the way. If authorities in other E.U. countries detain them, they can be forced to apply for asylum under far less-welcoming circumstances. Hungary has strung up a razor-wire fence along its frontier with Serbia, and Hungarian leaders this week barred their onward journey to Austria. Germany, meanwhile, expects to take up to 800,000 asylum-seekers this year. Critics say that type of patchwork enforcement only fuels the demand for smugglers.

Migrants being held at a train station in Bicske, Hungary, have begun to protest the conditions of their detention, including refusing water. Journalists have also been removed from the platform when attempting to speak with the migrants. (Storyful)

“As it becomes more difficult to move in Europe, the cost for the migrants and the need for smugglers will go up,” said Tuesday Reitano, the head of the Global Initiative against Transnational Organized Crime.

There is a service for every price point, ranging in the hundreds of dollars for a choppy below-deck voyage across the Mediterranean to thousands of dollars for longer, more complex journeys, law enforcement officials said. In a smartphone era, many of the smuggling services are available on Arabic-language Facebook and other social media sites. Migrants also communicate with one another along the journey using messaging tools such as WhatsApp to warn about where police coverage is heaviest.

“The Syrians are managing their trips in a much more savvy way than any other group that we’ve seen in the history of migration, that I’m aware of,” Reitano said.

The trip is made by boat, foot, rail and bus — and over the more than 1,000 miles between jumping off points in Turkey and the safety of Germany, smugglers are almost always involved in at least part of the journey, law enforcement officials say. Swedish authorities think that 90 percent of refugees reaching their territory used smugglers to ease at least a part of their trip. European officials estimate that the business runs in the billions of dollars.

“In Turkey, the smugglers are much more media-savvy and they cater to a specific audience,” said Izabella Cooper, a spokeswoman for Frontex, the E.U. border policing agency. “On social media, you can simply look up what’s available, there’s a specific date, and a specific type of transportation being offered.”

Until earlier this year, the bulk of crossings came by sea, over the Mediterranean from northern Africa. Now the flow has shifted to the western Balkans, along routes that have long been used by human traffickers, but never at current volumes.

The sea journeys have drawn headlines with all-too-frequent capsized boats. But the Balkan routes also can carry great danger. There may be far more victims than the 71 suspected migrants who perished in the truck in Austria, authorities say. Most of the asylum-seekers making their way to Europe through the western Balkans pay smugglers for each leg of their journey ahead of time, giving their escorts little motivation to make sure they reach their destination safely.

“The Austrian case, and this may sound chilling, is just one case that we’ve uncovered,” said Engström, of the Swedish police. “Now this happens every day, probably every hour, not only that people are transported every day under really hard conditions, but also that they suffocate, but we don’t find them.”

In the few days since Austrian authorities began screening most truck traffic coming from Hungary, they have found several instances in which migrants were packed into vehicles in unsafe circumstances, Austrian Interior Minister Johanna Mikl-Leitner said this week.

And one man suspected of involvement in the 71 deaths in Austria had been sought by German authorities in connection with a human-smuggling incident a month earlier, said Peter Wiesenberger, a state prosecutor in the southern German district of Deggendorf. He said that German police had stopped a Citroen van on July 25 and found 38 Afghan migrants inside. The driver and a passenger escaped. The car’s temporary license plate was registered under the name of Metodi Georgiev, a 29-year-old Bulgarian national, according to local news reports.

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The saga of the Syrian family whose 3-year-old turned up dead on a Turkish beach

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