Who the officer is, and what the agency already knew.

Why background matters

An officer's past conduct may bear on credibility, on intent, and on what the officer's supervisors knew. An agency that was aware of repeated complaints against an officer and did nothing may bear responsibility of its own. Whether and how such evidence can be used is a legal question for the attorney, but it cannot be used at all unless someone finds it.

Court records

Prior civil rights lawsuits naming the same officer or agency are found in federal and state court dockets. The complaints, rulings, and settlements in those cases show what was alleged before, how the agency responded, and who testified. Criminal court records may show cases in which an officer's testimony was challenged or rejected.

Complaints, discipline, and certification

In states where they are public, internal affairs files and disciplinary records are requested directly. State peace officer standards and training boards maintain certification records, and many publish decertification actions. Prosecutors in some jurisdictions maintain disclosure lists of officers with credibility problems, commonly called Brady or Giglio lists.

Movement between agencies

Officers who leave one department under a cloud are sometimes hired by another. Tracing an officer's employment history across agencies can reveal earlier conduct that the current employer knew about, or should have discovered, when it hired the officer.