A novel analytical technique to detect chemical warfare agent (CWA) simulants in forensic samples is presented. Three G-agent type simulants that closely mimic real CWAs, namely dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP), and diethyl phosphoramidate (DEPA), and in addition a hydrolysis product, pinacolyl methylphosphonate (PMP), were utilized. Dilute solutions spotted onto six different forensic matrices were used to evaluate the capability of an active capillary plasma ionization source, which could be attached to the inlets of either a conventional benchtop ion trap mass spectrometer or a miniaturized ion trap mass spectrometer, under ambient conditions. The sample solutions and matrix surfaces were exposed for about 10–20 seconds at a distance of 1 cm from the plasma ion source inlet. This real-time methodology was found to have a shorter analysis time than previously reported techniques. A full method validation, quantitative studies, and optimization for detection of real CWAs on forensic matrices should be done in the future.