After a full year of trying to get a leak fixed, I got help from a neighbor's roofer, who "knew a guy."  He said the guy didn't work on roofs, so I was confused!
Exactly!  The roofer told me that since I replaced my roof and the leak was still there, the problem had to be my fireplace chimney.  He said stone chimneys often develop leaks.  As it turns out, this chimney guy fabricates a type of gutter for chimneys to keep the water from running down the rock.  For $300 he made and installed the "gutter" on site, and I have had NO leaks!