Police have charged a motorist with obstruction after a standoff on an Atlanta freeway that backed up traffic for miles, but no one has been charged with the armed robbery that triggered the dramatic episode.

Marietta police said Monday that 25-year-old Taylor Alexander Smith-Duffy remains a "person of interest" in the Friday robbery at a Walmart, but detectives are still trying "to make a determination if he was involved."

It wasn't clear whether Smith-Duffy has a lawyer who could speak for him.

Police stopped Smith-Duffy on Interstate 75 after they said his car matched the description of a grey Honda Civic suspected of being involved in the robbery. At the time, police said he was armed and not cooperating with officers.

Police haven't said whether any gun was found.