A Nigerian man has been sentenced to more than 12 years in US prison for orchestrating an advance payment scam that bilked victims out of more than $1.3m.

Okpako Mike Diamreyan, 31, was ordered to serve 151 months in federal prison and pay a little more than $1m in restitution to the 67 victims he was was convicted of scamming from 2004 and 2009. The rare conviction was the result of his relocation to the US in 2008, when he married an American citizen. Rather than capitalizing on the opportunity to start a new life, he used it to ramp up his email-based scheme, which is often referred to as a 419 scam, after the Nigerian penal code that makes them illegal.

“i want to forget america and come back home . . . once i take like 1m or half m i don forget this place,” Diamreyan told an accomplice, according to court records. He routinely referred to his marks as "mugu," which means "fool" in Nigerian pidgin.

According to prosecutors, Diamreyan and his accomplice worked doggedly to dupe their victims, calling one victim more than 1,200 times over a two-year period. He claimed to have various consignments stored in Ghana worth millions and promised his marks a 20-percent commission in exchange for financial help in transferring funds to the US. To back up his claims, he provided fraudulent documents.

Ironically, the Nigerian citizen, who sometimes resided in Ghana, only stepped up the scam once he moved to the US, since many of the victims were more comfortable dealing with a person who was already on American soil, prosecutors said. Many of the marks were conned out of hundreds of thousands of dollars.

The prison sentence was at the low end of the 151 months to 188 months prosecutors had sought. The feds argued that a stiff sentence was necessary because Diamreyan was otherwise likely to return to Nigeria, where he would be free to continue the scam with impunity.

“Therefore, the only way to protect the public from further crimes by the defendant is to incarcerate him for a lengthy period of time,” they wrote in a sentencing memorandum.

Prosecutors said the $1.3m loss to victims was a conservative estimate, because it included only those who had direct dealings with Diamreyan. The feds conceded the likelihood of him paying the restitution was slim.