This research examined the relationship between adult missing persons and suicide, considering a number of possible vulnerability indicators/characteristics of this group of missing persons. Implications for missing person investigations were also explored, particularly for the risk assessment process. Data was extracted for 93 (N = 93) missing persons cases from one English police force, over a 4-year period. These individuals were found dead suspected of suicide. The findings illustrate a number of vulnerability indicators/characteristics of missing persons who complete suicide. In relation to the initial risk assessment level applied to the missing person report, two vulnerability indicators, a risk of suicide and the presence of a suicide note, had an effect on predicting a higher risk assessment level. Future research, in order to overcome the present study’s limitations, should attempt to collect data from more than one police force in order to increase the sample size. In addition to this, it would be beneficial to use a sample of missing persons who are found safe and well as a comparative sample to have a better chance in understanding the examined relationship and whether the vulnerability indicators/characteristics are indicative of suicide risk. The findings of this study have practical implications for the risk assessment process and are a step forward in providing empirical evidence applicable to identifying missing persons most at risk of suicide. This research has helped to build upon and corroborate existing knowledge of missing persons who complete suicide. This study provides new empirical evidence on suicide in adult missing persons. The findings demonstrate the subjective and variable nature of the risk assessment process and highlight potential implications on missing person investigations.