The victims reported collective losses of .4 million, which is likely only a fraction of the actual losses since many victims are too embarrassed to file a report, the FBI said.
About 70% of the victims were female; more than half were women 40 years or older.
More recently, casual dating hook-up apps like Tinder and Grindr emerged.
"Sexual assault is a crime, full stop, and we want victims to feel confident reporting it to the police." Guidelines for staying safe during online dating are available from nonprofit Get Safe Online.
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In a typical con, the perpetrator will spend weeks or even months building up a romantic relationship with a victim through e-mails, texts or phone calls, before eventually asking for money.
And many of the scammers aren't even in the United States.