Jon's Grandfather Is Still Alive ... Or Is He?

The letter said: Dear Jon, The artifact that was sent to you was *not* sent by me. Yes, Jon. I'm still alive and well. The artifact was stolen from me while I was in South America. Unfortunately, information about myself and you and your family were somehow taken from me. And for some reason or another, the artifact was sent to you. Jon, if you have received this artifact, then please meet me at the address at the top of this letter. I would really like to see you again. Your friend, always, Grandpa ----- Jon wasn't sure what to think. He attended his grandfather's funeral. If he was still alive, then who did they bury? He *did* want to see his grandfather, if he wasn't dead, but what if *this* was the fake letter, and someone just wanted to steal the stone from him?