DeKalb County police have charged a fourth suspect in last month's killing of an armored car guard during a robbery in Toco Hill Shopping Center.

Police charged 19-year-old Ronny Little with murder and aggravated assault yesterday, according to a police statement. He is being held in DeKalb County Jail.

Little joins three others who have been charged in the March 15 killing of Gary Castillo, a 32-year-old Garda armored car guard who was shot several times while leaving a Kroger grocery store with a cash pick-up. Edward Thornton, 28, Ashley Henderson, 27, of Atlanta and Stacey Dooley, 34, of Snellville were all charged in the killing late last month.

The same three and 34-year-old Quinton Booker of East Point also face armed robbery, aggravated assault and possession of a firearm by a convicted felon charges for another armored car robbery in Redan on Jan. 21.

The Toco Hill robbery was one of a string of armored car robberies across the metro Atlanta area that began in September. The FBI and local police departments have been investigating the spree since.