A jury duty scam that has ramped up in Tarrant County over the last month has prompted authorities to release warnings to the public.

Paula Morales, who oversees jury services for Tarrant County, said the county took more than 30 reports from residents who received calls from the scammers in May. She said the jury services office and the county district attorney's office feel like they have only heard about the tip of the iceberg with this scam, as well.

Here is how it works: Swindlers call unsuspecting citizens and tell them there is a warrant out for their arrest for failing to appear for jury duty. The caller tells the victims they can pay their fines, which tally upwards of $4,000, by getting a Green Dot money card and giving the caller the numbers over the phone.

The approach is designed to be as unsettling as possible, Morales said.

"One of the things that's really hard to grasp is that when the person calls them, they're being very belligerent, intimidating and threatening," Morales said. "They give them just enough real information to sound convincing. They know enough details that sound real that people are so caught off guard."

She said in many instances the callers will stay on the line until victims get the money card and then change their tone considerably, offering the victims an "easy way" to handle the situation by giving the numbers over the phone. Reports have come in from as far away as Florida, making the issue a federal offense if perpetrators are caught at this point, Morales said.

Tarrant County's Jury Services office would never contact a person by phone to pay a fine for failing to appear for jury duty, according to a news release on the scam. The office would send a notice before taking any other action, and if a warrant is issued, there is no warning phone call or fine payment in lieu of jury service. In fact, a fine can be assessed, and a jail sentence can be levied in some cases, but jury service would be rescheduled to a later date.

If a person is contacted about jury duty service and the Green Dot money card scam begins, they should write down the phone number of the caller, refrain from giving any personal information and contact their local police department to file a complaint, Morales said.