Americans sent more than $30 million to this Caribbean island last year to claim winnings in a Jamaican lottery. The trouble is there was no such contest.

Scam artists are making Jamaica a new center for internationally known lottery schemes, aiding a network of violent gangs that authorities say are putting the money into drug and gun trafficking.

The U.S. and Jamaica are now teaming up for a task force dedicated to breaking up the cross-border schemes. A formal announcement of the project is planned for Wednesday.

"It's just an incredible amount of money that's coming down here," said Vance Callender, an Immigrations and Customs Enforcement attache at the U.S. Embassy in Kingston. "We've got cases from Honolulu to Maine."

The scams were made famous by criminals in Nigeria: A caller says you have won millions in an overseas lottery, but he needs you to wire a few hundred dollars to cover the taxes. Payments only lead to other requests for money. As victims try to recover losses, scammers even pose as police and say they need cash to aid the investigation.

The schemes prey on compulsive impulses of victims who are often elderly.

"Some of these victims are just like gamblers," said Terrill Caplan, a Houston-based security officer for Fraud Aid, a nonprofit advocacy group. "They chase good money after bad, thinking the next one is going to be it."

Some have lost their life savings — including Ann Mowle, a 72-year-old retired bookkeeper from Monroe, New Jersey, who committed suicide in 2007 after reportedly losing $248,000 to a Jamaican lottery scam. Callender said his office is working with more than a dozen people who each have lost more than a half million dollars.

The Jamaican scams, which target the U.S. more than any other country, have grown dramatically over the last two years. Leslie Green, an assistant police commissioner, said gangs appear to be seeking new sources of revenue in response to a crackdown on drug trafficking.

Green said the rackets are contributing to a dramatic rise in violence in Montego Bay, a resort city where many of the scams are based.

The violence flares between gangs that discover they have purchased the same phone lists from brokers in the United States, according to Callender.

"They're targeting each other and killing each other to keep their lists virgin, basically," Callender said.

In the northwestern parish of St. James, which includes Montego Bay, murders have risen from 139 in 2005 to 214 last year while violence has held steady elsewhere in the Caribbean nation of 2.8 million people.

The millions of untraceable dollars also appear to have a corrupting influence on police. Last month, authorities suspended 19 officers in St. James who allegedly recruited a civilian to pose as a police officer in the service of a lottery scam. Green said other officers are under investigation for involvement in the schemes.

The new task force will seek the extradition of key suspects for trial in the U.S., Callender said. It will also try to return money to victims from cash seized as it comes into Jamaica and by liquidating criminal assets.

Already, U.S. agents have started intercepting payments from victims, according to Callender. He said $30 million is a conservative estimate of how much Jamaican scammers took from Americans last year.

For the victims, the losses have severe consequences.

Caplan said he met earlier this month with a Houston man in his 80s whose wife threatened to divorce him unless he stops wiring money to Jamaica.

The man, who did not want to be identified, has lost $121,000 — nearly all of the couple's savings — and they are now getting by on his wife's meager salary and his Social Security benefits.