What procedures do federal investigators follow for ballistics testing and chain‑of‑custody in officer‑involved shootings?
Executive summary
Federal investigators follow standardized evidence‑handling and forensic procedures in officer‑involved shootings: secure the scene, designate evidence handlers, document and preserve items, and forward firearm‑related items for ballistic comparison in accredited labs — all tied together by a documented chain of custody that preserves admissibility of ballistics, fingerprint and DNA findings [1][2]. When protocols break down—such as failures to transfer weapons to the FBI or to document custody—those gaps can jeopardize forensic reliability, admissibility in court and public confidence [1][2].
1. Scene control and evidence priority: securing what matters first
Federal protocols begin with immediate scene control and prioritization of safety, preservation of evidence and multi‑agency coordination; senior DHS and HSI officials say officer‑involved shootings typically involve immediate scene control and independent investigative leadership often coordinated with state and local authorities [1][3]. Practical guidance stresses that officer and public safety supersede evidence recovery, so items are photographed and documented in situ before removal, consistent with international and U.S. law‑enforcement guidance on firearms as evidence [4][5].
2. Designating handlers and documenting transfers to limit contamination
Best practices call for designating a single evidence handler, where practical, to limit chain‑of‑custody links and to document every transfer with time, person and condition notes; the IACP firearms guidance explicitly recommends one handler to preserve continuity and reduce risk of contamination [5]. The textbook definition of chain of custody underlines comprehensive documentation—who handled the evidence, when, and under what safekeeping conditions—to assure courts the item is the same as seized at the scene [2].
3. What gets collected: firearms, casings, GSR, and video evidence
Investigators typically collect the firearm, spent bullets, cartridge cases, gunshot residue samples, and related items, with bullets and casings photographed and packaged individually for transport to laboratories; firearms exam primers note that bullets, fragments and cartridge cases are collected and submitted to crime labs following chain‑of‑custody protocols [6][4]. Federal probes also review body‑camera and surveillance footage from multiple angles as part of reconstructing the shooting timeline and corroborating ballistic trajectories [1].
4. Ballistic testing and databases: NIBIN and lab comparisons
Ballistic comparison involves analyzing individual and class characteristics of spent bullets and casings to link them to a firearm and potentially to other crimes, and agencies use databases such as the ATF’s NIBIN for automated correlation; UNODC explains how striation and firing‑pin marks can identify a weapon and link evidence across scenes [4][5]. The FBI has developed rigorous ballistic testing protocols to simulate real‑world conditions, and such protocols often form the benchmark for evaluating performance and reconstructing shooting scenarios [7][5].
5. Lab roles, limitations, and interagency handoffs
Different federal agencies play distinct roles: HSI may lead investigative work but lacks some forensic lab capabilities, so the FBI or ATF typically conduct or coordinate ballistics, fingerprint and DNA testing; CBS reporting notes HSI’s limitations and that the FBI focuses on scientific forensic analyses [1]. Transfer of evidence to the appropriate forensic lab must be documented; failures to transfer weapons to the FBI or to record custody—reported in recent cases—raise questions about investigative integrity and can complicate prosecutions or civil litigation [1][2].
6. Failures, defense challenges and public trust
When chain‑of‑custody documentation lapses or weapons are not timely transferred for testing, those deviations become focal points for defense motions, civil‑rights suits and internal discipline reviews because admissibility and reliability of ballistics and DNA can be undermined [1][2]. The public debate over use‑of‑force is amplified when procedural breakdowns occur; federal policies on deadly force and their interpretation are themselves contested and factor into how evidence and ballistics findings are weighed [3][8].