The Compound Specific Analyzer Combustion Products, used on the International Space Station as a warning monitor of smoldering or combustion events, is being phased out of service. Southwest Sciences Inc. proposes to develop a replacement laser-based analyzer using wavelength modulation spectroscopic absorption. This device would be capable of real-time measurements of the four most important gases of interest (carbon monoxide, carbon dioxide, hydrogen cyanide, and hydrogen fluoride) at concentration levels relevant to pre-combustion events and with a 1 second response time. This battery-operated device would be hand-held, use very little electrical power, and have a multi-year lifetime without the need for consumables, re-calibration, or maintenance, in contrast to the currently-used analyzer. The Phase I research focused on what we believe are the most critical risks to using our approach. All of these objectives were successfully accomplished, laying a strong foundation for continuation of the research in Phase II. In Phase II, a fully functional prototype analyzer, meeting all of the requirements for operation in the International Space Station, will be built and tested. Issues relating to space-qualification will be identified so as to ease the transition to Phase III and subsequent development.