9.3 Criminal-Defense Investigation & Case Development

Criminal-Defense Investigation & Case Development

A defense investigation tests whether the government can prove the charged offense and develops facts relevant to defense, mitigation, suppression, negotiation, and trial. It is not an effort to make inconvenient evidence disappear.

Counsel direction and file protection

Obtain a written assignment from defense counsel identifying charges, elements, known deadlines, discovery, client-contact protocol, witnesses, scene, experts, and reporting method.

Attorney-client privilege belongs to qualifying confidential legal communications. Work-product protection depends on legal standards such as anticipation of litigation and direction. Hiring through counsel and limiting distribution can support protection, but neither a “privileged” label nor attorney payment guarantees it.

Follow counsel’s rules for notes, recordings, reports, secure delivery, conflicts, and subpoenas. Tell counsel immediately about evidence or information that creates ethical, safety, or preservation issues.

Case theory and timeline

Begin with neutral questions:

• What must the prosecution prove?
• What evidence supports each element?
• What facts are disputed?
• What alternative explanations fit?
• What source could confirm or refute each proposition?
• What deadlines threaten loss of video, phone, vehicle, business, or location data?

Build a master chronology with source citations. Separate allegation, witness statement, physical evidence, expert interpretation, and established fact. Include events that hurt the proposed defense.

Discovery review

Inventory reports, recordings, body-camera files, dispatch, photographs, forensic reports, warrants, returns, interview recordings, jail calls, digital extractions, and court filings. Track missing attachments and unreadable files.

Do not assume a police-report summary equals the underlying video or witness words. Compare timestamps, identities, measurements, and quoted language. Preserve the discovery as received and annotate working copies.

Questions about prosecution disclosure duties, protective orders, and discovery enforcement belong to counsel. The investigator identifies gaps and factual leads.

Witness interviews

Contact witnesses truthfully and respectfully. A witness may decline. Do not suggest that the investigator represents the court, prosecutor, or police. Do not threaten subpoena, prosecution, immigration action, or publicity.

Obtain free recall before showing reports or revealing the defense theory. Ask about opportunity to perceive, prior statements, outside discussion, media exposure, bias, uncertainty, and documents. Preserve exact important language and the questions asked.

A witness who changes an account is not automatically lying. Document each version, prompt, date, and possible explanation. Provide both favorable and unfavorable information to counsel.

Never pay for favorable testimony or coach a witness to omit facts. Reasonable expenses or professional expert fees require counsel’s approval and must not depend on content.

Scene investigation

Confirm whether the scene is public, private, or controlled by law enforcement. Obtain valid permission and do not cross a police barrier. Photograph overall orientation, sightlines, lighting, obstructions, distances, cameras, traffic controls, and changes since the event.

Reenactments require caution: conditions, positions, speed, weather, and lighting must be comparable and safety controlled. Label demonstrations as demonstrations, not original-event recordings.

If potential physical evidence is found, photograph it in place, prevent unnecessary disturbance, and contact counsel and the proper authority. Do not remove contraband, a weapon, biological material, or an item from an active scene merely to help the defense.

Identification evidence

Document the witness’s original description before any identification procedure, confidence language at the time, viewing conditions, delay, lineup or show-up procedure, feedback, and later exposure to the suspect’s image.

Do not conduct an amateur lineup that suggests the client. Counsel may retain a qualified expert when perception, memory, or procedure requires specialized analysis.

Alibi and digital leads

An alibi requires a timeline and independent sources: witnesses, receipts, video, access logs, work records, transportation data, and lawfully obtained device or account records. Confirm time zones and clock variance.

Do not log into another person’s account or alter a client device. Use consent, provider preservation, subpoena, warrant litigation, or qualified forensic acquisition through counsel.

A “missing” digital record is not proof of deletion. Identify retention policies, system gaps, and what was requested.

Reports and testimony

Use counsel’s reporting protocol. Some counsel prefer prompt oral updates followed by focused memoranda; others require full reports. Professional-rule duties still require objectivity and relevant information.

A report can include:

• task and source;
• actions and dates;
• witness account and recording status;
• scene observations;
• exhibits;
• conflicts;
• preservation steps;
• unresolved leads; and
• limits.

An investigator can become a fact witness. Assume that methods, notes, compensation, and inconsistencies may be examined. Never write or act in a way that depends on secrecy from the court.

Mitigation

Mitigation investigation can cover history, trauma, health, education, military service, family, community, treatment, and future planning. It requires informed, trauma-aware interviews and corroborating records. It is not an excuse to diagnose beyond competence or disclose sensitive material outside counsel’s strategy.

Exam method

Choose counsel-directed lawful collection, objective testing, voluntary nonleading interviews, scene authorization, evidence preservation, and full reporting of adverse facts. Reject witness coaching, unauthorized account access, evidence removal, and guaranteed outcomes.