First the cartel cut its teeth with drug trafficking. Then avocados, real estate and construction companies. Now, a Mexican criminal group known for its brutality is moving in on seniors and their timeshares.

The operation is relatively simple. Cartel employees posing as sales representatives call up timeshare owners, offering to buy their investments back for generous sums. They then demand upfront fees for anything from listing advertisements to paying government fines. The representatives persuade their victims to wire large amounts of money to Mexico — sometimes as much as hundreds of thousands of dollars — and then they disappear.

The scheme has netted the cartel, Jalisco New Generation, hundreds of millions of dollars over the past decade, according to U.S. officials who were not authorized to speak publicly, via dozens of call centers in Mexico that relentlessly target American and Canadian timeshare owners. They even bribe employees at Mexican resorts to leak guest information, the U.S. officials say.

The scam represents the latest evolution of the Jalisco New Generation, which is entrenched in both illegal and legal sectors of the economy. With little more than a phone and a convincing script, cartel employees are victimizing people across multiple countries.

And even those employees are vulnerable to the cartel’s ruthlessness.

Last May, the remains of eight young Mexicans who worked at a call center owned by the cartel were discovered in dozens of plastic bags in a ravine on the outskirts of Guadalajara, a city in Jalisco state.

The cartel typically preys on older, retired people who want to leave as much money as they can to their family by selling off assets. Several victims interviewed by The New York Times said the money they had lost to scammers exceeded the value of their initial investment in timeshares in Jamaica, California and Mexico.