Investigators say Richburg, of the 2000 block of South Norwood Street, was arrested after an anonymous tip was called into 911.
Richburg was arrested without incident by U.S. Marshals and Philadelphia Police Homicide Unit. He will be charged with murder and related offenses.
Police say Hargrove and Richburg entered Trax Foods on North Front Street early morning on May 26th.
50-year-old Mustafa Shaker was on duty at the time as the suspects demanded money.
Surveillance video released by police shows Shaker wouldn't open the register. Police say one of the suspects then shot Shaker in the head.
Anyone with information is asked to contact the Philadelphia Police Homicide Unit at 215-686-3334/3335.