It often started with a hope for love, then quickly turned into a promise of gold. In one tragic case, it ended in death.

A woman had struck up a romance on a dating website with a man who said he was a US soldier stationed overseas.

He claimed to have more than $12 (£9.8) million worth of gold from Syria but needed help bringing it to the United States, so she sent him $93,000 (£75,640).

He sent back a photograph of an Israeli diplomat she was supposed to meet at the Baltimore airport who was going to bring her “two trunks with ‘family treasure’”, according to a criminal complaint.

But he never showed up. The next day, she killed herself.

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The US attorney for New Jersey has said that the woman’s death was part of a complex and brazen fraud that swindled more than 30 people out of about $2.1 (£1.71) million.

The scheme was run by two people in New Jersey and their associates in Ghana.

It usually involved someone posing as an American service member on a dating website and “wooing” a target “with words of love”, according to the complaint.

While internet frauds have persisted for years, the breadth of the swindle stands out, as well as the fact that it led to arrests.

On Wednesday, the FBI arrested one New Jersey man, Rubbin Sarpong, for conspiracy to commit wire fraud.

If convicted, he could face up to 20 years in prison and $250,000 (£203,400) in fines. A lawyer for Mr Sarpong did not respond for comment.

The case also comes amid growing scrutiny of the proliferation of this type of fraud and struggles by tech companies and the military to stop them.

The New York Times reported in July that similar swindles were rampant on Facebook, Instagram and other platforms.

Hundreds of profiles were found that impersonated military service members and veterans, including the nation’s top generals.

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Following The Times’ reporting, congressman Adam Kinzinger said he was considering legislation to force Facebook and other companies to do more to prevent such frauds.

Mr Kinzinger, who is also in the Air National Guard, said scammers have used his likeness for years to defraud people online.

On Thursday, he criticised Facebook for its announcement that users in the United States could now create dating profiles on its platform.

Facebook said the service, Facebook Dating, was already available in 19 countries – including Brazil, Canada and Vietnam – and it was aiming for a European release next year.

“Rather than compound this issue with a dating platform, Facebook should focus its attention and resources on putting a stop to the scams and fake accounts,” he said in a statement.

Facebook, which owns Instagram, has said it requires people to use their real identities on its sites, although it does not require proof.

To eliminate impostor accounts, the company has said it invested in more human reviewers and new software to automatically spot fakes. Facebook has said it blocked billions of fake accounts over the past year, though its estimate for the number of active fakes has continued to increase to roughly 120 million.

A Facebook spokeswoman did not immediately respond for comment.

Mr Sarpong’s arrest this week comes on the heels of a separate case last month in which federal authorities charged 80 people, accusing them of involvement in a Nigerian crime ring that stole at least $6 (£4.88) million via email, romance and other internet swindles.

Fourteen people were arrested in the United States, but scores of other suspects are not in the country.

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The two recent cases are unusual because scammers are often able to stay out of reach of US law enforcement since they are based abroad, often in West Africa, said Patrick Peterson, chief executive of Agari, a cybersecurity firm that tracks internet fraud.

“What makes this very unique,” he said, “is Mr Sarpong lives in New Jersey, and his co-conspirators are still safe and sound in Ghana, with hundreds of thousands of dollars in proceeds.”

Mr Peterson said the two cases suggested that US authorities were trying to do more to combat such romance frauds, which data shows are increasing.

The FBI said it received nearly 18,500 complaints from victims of romance or similar internet frauds last year, with reported losses exceeding $362 (£294.5) million, up 71 per cent from 2017.

Law enforcement is “starting to crack the code on how to do this repeatedly and at scale, and they’re trying to invest more because the losses are so high”, Mr Peterson said.