Or they may ask you to pay fees, charges or taxes to 'help release or transfer the money out of the country' through your bank.
If a victim makes the payment, the fraudster either invents a series of further fees for the victim, or simply disappears.
There are many variations on this type of scam, including the 419 scam, the Spanish Prisoner scam, the black money scam, Fifo's Fraud and the Detroit-Buffalo scam.
These scams are often known as 'Nigerian 419' scams because the first wave of them came from Nigeria.
The '419' part of the name comes from the section of Nigeria’s Criminal Code which outlaws the practice. Scammers may ask for your bank account details to 'help them transfer the money' and use this information to later steal your funds.
The scam has been used with fax and traditional mail, and is now prevalent in online communications like emails.