Deaths of suspects or inmates while in custody and incarceration is a tragedy for families and could become a public issue. Such deaths occur within a complicated brew of ethical and legal hurdles that must be handled with caution. We conducted a survey about these deaths. We collected and reviewed 85 cases of death that occurred while in custody and incarceration in Seoul and the Gyeonggi province, including e postmortem examinations between 2004 and 2011. Natural causes (most commonly cardiovascular diseases) accounted for nearly half of the deaths in custody, and unnatural causes accounted for nearly all of the remainder. Suicidal strangulation (hanging and self-strangulation) was the most common cause, followed by poisoning. Natural deaths by cardiovascular disease and unnatural deaths by suicidal strangulations, poisoning accounted for most cases of death while in custody and during incarceration. We hope this study can facilitate policy proposals to address this problem, helping authorities to reduce the occurrences of these preventable and untimely deaths of individuals in custody and incarceration.