Friday, agents with Tennessee Bureau of Investigation arrested Samuel Watkins, 31, and charged him with one count of theft over $10,000. He was booked into the Fayette County Jail.
The investigation by TBI revealed that Watkins helped plan the robbery, and drove Christopher Lee to the gas station on Highway 64.
Lee and Jessica Gardner, who was the clerk at the gas station, have already been arrested. Watkins and Gardner are an engaged couple, Fayette County authorities said.
According to TBI, Lee walked onto the station parking lot Thursday morning and took the deposit bag from Gardner. Lee ultimately encountered two law enforcement officers responding to the robbery call, and shots were exchanged, injuring a deputy.
Lee fled the scene in a stolen car and crashed that vehicle at Highway 64 and Rockcreek Parkway in Cordova, and was taken into custody.
The initial investigation determined that Gardner was aware of, and helped plan, the robbery.
Lee was arrested later Thursday after a stint in the hospital, and Gardner was arrested around the same time. Watkins turned himself in Friday morning.
All three are charged with theft, with Lee facing additional charges like attempted murder.
Watkins has a few older charges in Fayette County, while Gardner has none. Lee has a lengthy criminal history in Shelby County, including an aggravated robbery charge from last year.
Deputy Jimmy Pardue is expected to be OK.