How Private Investigators Help Attorneys Build a Case

Published August 1, 2026

When an attorney takes on a complex civil dispute, a criminal defense matter, or a contentious family law case, courtroom skills alone are rarely enough. Building a strong case often requires digging up facts that are not sitting in a filing cabinet waiting to be found. That is where a licensed private investigator comes in. PIs who work alongside legal teams serve as skilled fact-finders, operating within the boundaries of the law to gather the information attorneys need to advise clients and present arguments effectively.

The Role of a Private Investigator in Legal Cases

Private investigators are not a substitute for an attorney, and attorneys are not investigators. The two roles complement each other. An attorney develops legal strategy and argues the law; a private investigator gathers the factual raw material that strategy is built on. Working together, they can move a case from speculation to documented evidence.

It is worth noting from the start that investigators must operate entirely within the law. They cannot trespass on private property, intercept communications, hack into accounts, impersonate law enforcement, or access protected records without proper authorization. Any evidence gathered through illegal means is not only inadmissible in court—it can expose both the investigator and the attorney to serious legal consequences. A reputable PI understands these boundaries thoroughly and stays well within them.

Key Ways PIs Support Attorneys

1. Locating and Interviewing Witnesses

Witnesses move, change phone numbers, and sometimes actively avoid contact. A licensed PI has legitimate tools and techniques to locate people—searching public records, databases of addresses, and other lawfully accessible sources. Once a witness is found, a skilled investigator can conduct a thorough interview, document what the person says, and assess their likely credibility before the attorney invests time in a deposition or subpoena.

2. Serving Legal Process

Process serving—delivering subpoenas, summonses, and other court documents—is a task many private investigators handle routinely. Proper service is a legal requirement, and a professional PI knows how to complete it correctly and provide the affidavit of service that courts require. This is especially valuable when a subject is difficult to locate or is actively evading service.

3. Conducting Surveillance

In personal injury, workers' compensation, and insurance fraud cases, attorneys may need documented evidence of a claimant's actual physical condition and activities. A licensed PI can conduct lawful surveillance in public spaces—observing and recording what anyone in that location could plainly see. This might mean videotaping a person at a park, a grocery store, or a sporting event when their claimed injuries suggest they should not be capable of such activity.

Surveillance has clear legal limits. Investigators cannot photograph or record people inside their homes, follow someone onto private property without permission, or place GPS tracking devices on a vehicle without legal authorization to do so. Laws on electronic surveillance and tracking vary significantly by state, so working with a locally licensed investigator matters. In Texas, for example, the state's private security licensing board sets specific requirements for investigators, and investigators must comply with both state and federal law on surveillance and recording.

4. Background Investigations

Attorneys may need background information on opposing parties, expert witnesses, potential business partners in litigation, or even jurors during voir dire research (where permitted by law). A PI can compile lawfully obtained background information—civil and criminal court records, business filings, professional license history, and more—from public sources. The Federal Trade Commission publishes guidance on how background screening must be conducted responsibly and what consumer protections apply, which a reputable investigator will follow.

5. Locating and Documenting Assets

In divorce proceedings, business disputes, and judgment collection matters, attorneys often need to know what assets the other party actually holds. A PI can search public records—property filings, business registrations, court judgments, and similar documents—to build a picture of a person's financial holdings. This is especially useful when a party is suspected of hiding or undervaluing assets.

6. Gathering Evidence in Family Law Cases

Child custody disputes and divorce cases are among the most emotionally charged matters an attorney handles. A PI may be asked to document a parent's living situation, verify claims about lifestyle or behavior, or locate a parent who has taken a child out of the jurisdiction. As with all PI work, this must be done lawfully—through observation in public places, review of accessible records, and interviews with willing sources. For legal guidance on what courts consider relevant evidence in family law matters, resources like Nolo's legal information library offer a useful starting point.

7. Researching Expert Witnesses and Opposing Counsel's Case

Attorneys may ask a PI to research the background and prior testimony of an opposing expert witness, looking for inconsistencies, undisclosed conflicts of interest, or prior statements that contradict the expert's current position. This kind of thorough background work can be pivotal during cross-examination.

What to Expect When an Attorney Engages a PI

• A clear scope of work: A professional PI will agree in writing to what is being investigated, the methods to be used, and the expected deliverables.
• Regular reporting: Investigators typically provide written reports and any supporting documentation—photographs, video, records—in a format suitable for use in legal proceedings.
• Confidentiality: Work performed at the direction of an attorney may be protected under attorney-client privilege in certain circumstances. Your attorney can advise on how this applies to your situation.
• Realistic expectations: An investigator gathers information—they do not guarantee a particular outcome. Evidence may support your case or reveal uncomfortable facts that change strategy.

Verifying Licensing and Qualifications

Private investigators are licensed at the state level, and requirements vary considerably. Before working with any PI, confirm that they hold a current, valid license in the state where the investigation will take place. You can look up licensing requirements and verify credentials through official state agencies. The USA.gov government services directory can help you find your state's relevant licensing authority. In Texas, investigators are licensed through the Texas Department of Licensing and Regulation.

Questions to Ask Before Hiring

1. Are you currently licensed in this state, and can I verify your license number?
2. Do you have experience with cases similar to mine—civil litigation, family law, criminal defense?
3. What methods will you use, and how do you ensure they are legal?
4. How will you document findings and format your reports for court use?
5. What are your fees, and how will billing be structured?
6. Have you testified in court before, and are you comfortable doing so if required?

A Note on Legal Advice

If your situation involves potential litigation, custody decisions, criminal charges, or any matter with significant legal consequences, consult a licensed attorney before taking action. An attorney can advise you on what evidence is legally relevant, how it must be gathered, and whether engaging a PI is the right step for your specific circumstances. For general legal reference, Cornell Law School's Legal Information Institute provides accessible explanations of federal and state law across many practice areas.

Private investigators are a powerful resource for legal teams—not because they operate outside the rules, but precisely because they know how to work effectively within them. When the facts of a case are unclear, disputed, or hard to reach, a skilled PI can make the difference between building a solid evidentiary foundation and going to court empty-handed.

If you are an attorney or a party involved in litigation and would like to connect with a licensed private investigator in your area, you can request a no-obligation introduction through Find A Local PI. There is no cost to reach out, and you are under no pressure to hire.