"How these people are getting the exact names of these people's grandchildren is beyond me," Cropper said. "But that's what they are doing. They are actually getting someone on the line and acting like they are the grandchild."
The scammer then claims to need money for fines to get out of Mexican prison. If the victim wires the money, a different person calls back later claiming to be a lawyer needing more money for legal fees.
In one instance of the scam reported in California, the scammers not only knew the grandchild had a twin, but that their sibling had been born two minutes later.
In both local cases, the scammers knew their grandchild's name before they called. In the past scammers would only say things like, "Do you know who this is?" or, "Hello, it's your favorite grandchild!" but would not have any personal information.
The most recent victim lost $2,800 for only trying to help their "grandchild" out of a tough situation.
"I was so concerned about my grandchild being in jail in Mexico City, I just went to pieces over it," the victim said. "I should have known not to do that, but the only thing I thought of was my grandchild being in a Mexican jail and what could happen there."
They wired the money through a bank. Then another call came asking for $2,500, but the victim did not have the money to send.
While thinking about a few details of the first call, the victim realized something was amiss and contacted the police.
"People need to be aware," Cropper said. "If they get a phone call from a grandson saying he is in jail in Mexico, they need to ignore it and immediately try to make contact with their grandson to verify (the caller's identity)."
Cropper said they are investigating the scam calls, but money wired into Mexico is very difficult to trace.