This paper examines whether CIREN fatal cases are representative of crash fatalities in terms of injury patterns and the time to death. To examine the association, CIREN fatalities are compared with those of all motor vehicle crashes. Comparison data sets are derived from FARS data and from records obtained from the Maryland Office of the Chief Medical Examiner. Differences in injury patterns between those who died early-on vs. those who died later are documented. The findings suggest that the CIREN dataset is representative of real-world fatalities in terms of the fraction of deaths occurring within thirty minutes of the crash;​ and that, as expected, occupants who die early-on in CIREN are observed to have more severe injuries than those who die later. Moreover, injuries among early-on deaths appear to have a slightly different distribution than among those who die later. Also, CIREN has a higher fraction of cases where occupants died after twentyfour hours than in the U.S. population. The results of this study will help to refine methods used to estimate mortality associated with particular injuries by assessing the completeness of injury records for fatal cases.