BACKGROUND Mortality risk is elevated among people released from prison; however, comprehensive analyses of cause-specific death patterns and associated factors remain limited.

METHODS This retrospective cohort study analysed 1,511 deaths of people under post-release supervision in England and Wales (2019-2021) using standardised ICD-10 mortality classifications. For the 12-month post-release period, crude mortality rates (CMRs), age-standardised mortality ratios (SMRs) and temporal patterns were calculated. Demographic and criminogenic factors were analysed across causes of death.

RESULTS The all-cause CMR was 857 deaths per 100,000 person-years, with a higher rate among women (1260 [993-1544]) than men (825 [762-889]). Injuries accounted for 49% of deaths, with drug poisoning as the leading cause, accounting for 54% of deaths among women and 38% among men. SMRs revealed dramatic elevations compared to the UK population: drug poisoning (74.1 [38.4-153.2]), interpersonal violence (63.3 [11.3-264.3]) and suicide (9.9 [3.3-27.8]). Temporal trends followed a bimodal pattern, with rates peaking immediately after release and again after six months. Further demographic disparities emerged: interpersonal violence deaths characterised by young age and minority ethnic representation; non-communicable disease deaths concentrated in older groups. Women exhibited comparable suicide rates to men, contrary to general population trends. Social inequalities were evident, with acute deaths associated with housing instability, unemployment and breach of release conditions.

CONCLUSIONS Post-release mortality rates are very high, influenced by intersecting demographic, criminal justice, and social factors. Gender-specific approaches and cross-system coordination between health, justice, and social services are needed during imprisonment and the critical first year after release.