Asking for money to help get out of jail . Claims in for drunk driving and needs help from family  uses name Adam Ross

My mom got the same idiot called her 7/24/13. May I ask if you are an elderly person who might have been recently listed in someone's obituary. I have a theory.

Got a call from this individual that said he was in Mexico city on a fishing trip. First said he was my grandson but when I replied that I didn't have a grandson he said he was kidding and he was my nephew. He wanted money for an embarrassing situation. I asked him to tell me the name of his mother and father and he got all fluster and eventually hung up. Definitely a scam. How do you report this scam to the authorities?