A Maryland man was arrested Thursday on charges that he and other conspirators used dating Web sites to identify elderly men and women, then defraud them out of tens or hundreds of thousands of dollars.

Federal prosecutors say that Krist Koranteng, 32, worked with four other people to lure at least three victims into romantic relationships, using Match.com and Chemistry.com. The conspirators then convinced the victims to send money to accounts controlled by Koranteng.

The alleged conspirators gave the victims many reasons to send money: They would invest it in gold. They needed to pay hospital bills for sick relatives. They would spend the money on plane tickets to come visit the victims, with whom they had formed romantic relationships via e-mail, phone conversations and text messages.

The stories worked, prosecutors say. The indictment states that a victim who lived in West Virginia and Ohio deposited $22,000 in October 2012 into an account controlled by Koranteng. The same woman then transferred $90,000 to the account in February 2013, $80,000 in March and $250,000 to another account in April.

The indictment says that Koranteng sent her roses for her birthday in November, as well as e-mails around the same time to reassure her that the gold she had invested in was real. In December, she sent a check for $65,000.

The indictment says that another victim in Cleburne, Tex., deposited $30,500 in an account controlled by Koranteng, and a victim in British Columbia sent more than $30,000 by wire transfer.

Koranteng was arrested by Montgomery County police in January and charged with theft of more than $100,000. At that time, police seized $7,694 from him. The Circuit Court charges were dropped so that federal prosecutors could pursue their case, said Ramon Korionoff, a spokesman for the county state’s attorney’s office.

Since January, police have seized a total of more than $290,000 from 17 accounts, the indictment says.

The four co-conspirators named in the indictment have not been charged.

Koranteng’s attorney declined to comment. Koranteng is scheduled to appear in court again Monday.

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