Project Summary The national suicide rate has grown by 30% over the last twenty years, and nearly 46,000 people died by suicide in 2020. The rate of drug overdose death has grown even more dramatically over the same period. Nearly 108,000 people died by drug overdose in 2021, an all-time high. Substance use and suicidal ideation are strongly correlated. This overlap makes intent difficult for death investigators to classify in fatal drug overdoses. Consequently, many overdose deaths ruled unintentional or “undetermined” may in fact be suicide victims. This project will leverage data from death certificate, toxicology, police, and coroner/medical examiner reports to investigate how medicolegal death investigators classify intent within fatal drug overdoses. The data sample contains three states in a region with high rates of drug abuse and overdose death. With a mixed methods approach of quantitative and linguistic analysis, the project will first identify which factors are most predictive of intent classification. Potential factors include characteristics of decedents, death investigation systems, and the socioeconomic conditions of communities. The principal data sources are the National Violent Death Reporting System (NVDRS) and the State Unintentional Drug Overdose Reporting System (SUDORS). Both sources contain decedent-level information. Whereas NVDRS contains intentional deaths by drug poisoning (suicide), SUDORS contains unintentional (accidental) and “undetermined” deaths. The combination of these sources will provide novel insight on suicidal intent among fatal drug overdoses. The project will also develop a statistical adjustment to estimate underreported suicide deaths. This adjustment will build from a model of suicide deaths by drug poisoning (in NVDRS) to estimate rates of underreported suicide deaths in the unintentional and “undetermined” fatal overdose deaths (in SUDORS). The project will therefore help identify populations in critical need of mental healthcare access and treatment. Furthermore, unintentional drug overdose deaths and suicide deaths require a different set of prevention strategies and policies. Accurate mortality surveillance systems are therefore central to either prevention effort. The analyses in this project will inform points of intervention for death investigator instruction on the important classification of intent within fatal drug overdoses.