Before the Arrest: Benchmarking LLMs on Criminal Profiling from Incomplete Evidence

Yutong Yao, Cao Yanjie, Guanhua Chen, Yang Xu, Junchao Wu, Zeyu Wu, Lidia S. Chao, Derek F. Wong


Abstract
Large Language Models (LLMs) are increasingly applied to legal and criminal justice tasks, yet existing work focuses almost exclusively on post-arrest scenarios where the suspect’s identity is already known, leaving the critical pre-arrest challenge of inferring suspect characteristics from incomplete evidence largely unexplored. To fill this gap, we introduce the Profiling, Investigation, and Judgment (PIJ) benchmark, comprising 2,500 real homicide cases from five countries. PIJ evaluates LLMs across three tasks that span the entire criminal investigation pipeline: criminal profiling, which requires abductive reasoning to infer suspect attributes from fragmentary scene evidence, crime process reconstruction, which tests structured information extraction, and sentence prediction, which demands legal deductive reasoning. We evaluate 9 powerful LLMs and find that performance degrades systematically as tasks shift from explicit fact extraction to implicit reasoning over unknown suspect profiles. Categories requiring inferential reasoning, such as motivation and victim-offender relationships, remain the primary bottlenecks. Further analysis reveals substantial gaps between LLMs and human experts, along with pervasive biases in gender, age, and motive attribution. Our findings indicate that current LLMs are far from ready for practical deployment in criminological investigation.
Anthology ID:
2026.findings-emnlp.2263
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
48462–48483
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2263/
DOI:
Bibkey:
Cite (ACL):
Yutong Yao, Cao Yanjie, Guanhua Chen, Yang Xu, Junchao Wu, Zeyu Wu, Lidia S. Chao, and Derek F. Wong. 2026. Before the Arrest: Benchmarking LLMs on Criminal Profiling from Incomplete Evidence. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 48462–48483, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Before the Arrest: Benchmarking LLMs on Criminal Profiling from Incomplete Evidence (Yao et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2263.pdf