In forensic casework, non-invasive and minimally-invasive methods for postmortem examinations are extremely valuable. Whole body postmortem computed tomography (PMCT) is often used to provide visualization of the internal characteristics of a body prior to more invasive procedures and has also been used to locate gas reservoirs inside the body to assist in determining cause of death. Preliminary studies have demonstrated that exploiting the volatile organic compounds (VOCs) located in these gas reservoirs by comprehensive two-dimensional gas chromatography-high-resolution time-of-flight mass spectrometry (GC×GC-HRTOF-MS) may assist in providing information regarding the postmortem interval. The aim of the current study was to further develop the procedures related to solid-phase microextraction (SPME) and GC×GC-HRTOF-MS analysis of gas reservoirs collected from deceased individuals. SPME fiber extraction parameters, internal standard approach, and sample stability were investigated. Altering the SPME parameters increased the selectivity and sensitivity for the VOC profile, and the use of a mixed deuterated internal standard contributed to data quality. Samples were found to be stable up to 6 weeks but were recommended to be analyzed within 4 weeks due to higher variation observed beyond this point. In addition, 29 VOC markers of interest were identified, and heart and/or abdominal cavity samples were suggested as a possible standardized sampling location for future studies. The data presented in this study will contribute to the long-term goal of producing a routine, accredited method for minimally-invasive VOC analysis in postmortem examinations.