BLAIRSVILLE, Georgia (CNN) -- The person of interest in the disappearance of a hiker in the north Georgia mountains is in custody and is being questioned by the Georgia Bureau of Investigation, police announced Friday evening. Gary Michael Hilton, 61, was detained after a police officer spotted his van at a convenience store. Investigators also have another piece of the puzzle: Meredith Emerson's black Labrador retriever, Ella, who walked into a grocery store Friday. The animal was positively identified through an embedded microchip. The search for Emerson will continue Saturday. -snip-