1. A security screening system comprising: a main housing; a contact pad provided on the main housing; a sample collection sheet positioned upon the contact pad, said sample sheet receiving a trace residue sample upon contact with a subject; a pressure sensor operatively linked to the contact pad, said sensor configured to determine a pressure applied to the contact pad during a sample collection process; a sample processing system provided in the main housing, said sample processing system analyzing the sample collection sheet to determine whether the trace residue sample contains a threat residue; and a spatial recognition system operatively connected to the sample processing system, said spatial recognition system configured to focus the sample processing system on particular portions of the sample collection sheet.