The man thought to be the so-called “Back Room Bandit” — a thief who struck stores in the Midway area, La Jolla and elsewhere in San Diego — has been slated for a Dec. 15 preliminary hearing to face 20 robbery counts. Dragon Jones, 41, has pleaded not guilty in San Diego Superior Court on charges he held up Pet People stores on Midway Drive and on Villa La Jolla Drive, along with 18 other robberies investigators say they have linked him with. Jones was arrested Nov. 1 as he entered the San Ysidro border crossing area. Deputy District Attorney Amy Maund said the robber selected small stores all over the county in which there were mostly women working, often with just one employee at a cash register. The suspect pulled a gun and ordered the clerks to open the cash registers, sometimes saying he would shoot them if they hesitated. The stores included yogurt and sandwich shops, beauty supply stores, a pizza restaurant, craft and card stores spread across San Diego, National City, Chula Vista, El Cajon, La Mesa and Lemon Grove. The robberies began Sept. 25 and ended Oct. 29. “There is an ongoing investigation,” said Maund, who indicated more charges might be filed. Jones appeared Nov. 12 before a judge, who set the preliminary hearing for Dec. 15. Maund said an investigation led by National City police determined the robber’s identity through fingerprints apparently left at one scene. Investigators said they knew Jones was going back and forth into Mexico. If convicted of all charges, Jones faces a maximum 24-year prison term. He remains in custody on $750,000 bail.