Police are still looking for several other men who took part in the robberies, during which they usually wore masks, hooded sweatshirts, gloves, and dark clothing.
The robbers typically entered wielding a silver Ruger .40-caliber semiautomatic weapon, held the clerk at bay, and stole cash and cartons of Newport or Marlboro cigarettes and other tobacco products, officials said.
Walls was charged in robberies June 3 in Evesham and June 12 in Gloucester Township. Charges include first-degree armed robbery, theft, unlawful possession of a firearm, and unlawful criminal restraint. He is being held in the Camden County jail.
The Prosecutor's Office said the robbers' repeated use of the same late-model Chevrolet Sonic led them to Walls.
Detective Vince McCalla spotted the car in several grainy videos, according to officials, and obtained the records on all recent vehicles of that make registered in the state. The list ran to the thousands, but McCalla eliminated those whose color, geography, markings, and other details made them unlikely candidates.
With the list narrowed to 33, he surmised that any such vehicle involved in frequent motor vehicle violations might point to someone with a flagrant disregard for the law.
That research pointed to Walls, according to officials, and on June 12, Cherry Hill police assigned a surveillance team to watch him and the car.
Although they were forced to break off the surveillance when it appeared Walls realized he was being followed, authorities said, the car showed up later in the day on surveillance video from a robbery at a 7-Eleven in Gloucester Township. One of the robbers also appeared to be wearing the same clothing Walls had worn.
Police arrested him the next day and reportedly recovered the Ruger .40-caliber semiautomatic weapon that appeared to have been used in the January shooting, along with zip ties and rubber gloves similar to those used in several robberies.
During their spree, the robbers hit one store each in Pennsauken, Moorestown, Medford Lakes, and Gloucester Township, and two in Cherry Hill and Evesham.