How Private Investigators Help Attorneys Build a Case

Published August 8, 2026

When an attorney takes on a complex case, the work of building a strong legal argument rarely falls to legal counsel alone. Private investigators are frequently brought in as professional partners to gather facts, locate people, and document information that can make or break a case in court. Understanding how this relationship works can help you — whether you are an attorney looking for support or a client wondering why your lawyer has recommended hiring an investigator.

The Role of a Private Investigator in Legal Cases

Private investigators who work with law firms are sometimes called litigation support investigators. Their job is to find and preserve factual information that attorneys can use to advise clients, negotiate settlements, or present evidence at trial. They do not practice law, offer legal opinions, or guarantee any particular outcome — they gather information and report what they find.

It is important to understand what investigators can and cannot do. A licensed private investigator must operate entirely within the law. They cannot:

• Trespass on private property to obtain evidence
• Intercept phone calls or electronic communications without consent where the law prohibits it
• Access protected government, financial, or medical records through unauthorized means
• Impersonate a law enforcement officer
• Place a GPS tracker on a vehicle they do not own or have permission to track, in jurisdictions where this is restricted
• Hack into computers, email accounts, or cloud storage

Any evidence gathered illegally is likely inadmissible and could expose both the investigator and the attorney to serious legal consequences. A reputable investigator will always make the legal boundaries of their work clear upfront. For general legal reference on privacy rights and surveillance law, Law Cornell's Legal Information Institute offers a solid starting point.

Key Ways Investigators Support Attorneys

1. Locating Witnesses and Hard-to-Find Individuals

One of the most common tasks attorneys assign to investigators is finding people — witnesses who have moved, defendants who are avoiding service of process, or heirs in probate matters. Investigators use legal database searches, public records, and fieldwork to track down individuals and verify current addresses and contact information.

2. Serving Legal Documents

Process serving — delivering subpoenas, summons, and other court documents — is a function many licensed investigators perform. Proper service is a legal requirement, and an experienced investigator knows how to document service in a way that will hold up in court.

3. Conducting Surveillance

In personal injury, workers' compensation, divorce, and insurance fraud cases, surveillance can be a critical tool. A licensed investigator can legally observe and photograph or video-record individuals in public spaces where there is no reasonable expectation of privacy. This type of evidence can corroborate or contradict claims being made in litigation.

Licensing requirements for surveillance work vary by state. In Texas, for example, private investigators must hold a license issued by the Texas Department of Public Safety and are subject to specific rules governing how they may conduct their work. Always confirm that any investigator you or your attorney hires holds the appropriate license for your state.

4. Gathering and Preserving Digital Evidence

Social media posts, online activity, and publicly available digital records can be valuable in litigation. Investigators trained in open-source intelligence (OSINT) know how to find, capture, and preserve this material in a format that maintains its integrity for evidentiary purposes — including proper timestamps and chain-of-custody documentation.

5. Background Investigations

Attorneys may need a thorough background investigation on a witness, opposing party, or potential business partner involved in a dispute. Investigators compile information from public records, court filings, and legal databases to build an accurate profile. The Federal Trade Commission publishes guidance on how background screening must comply with federal law, which a qualified investigator will follow carefully.

6. Asset Searches

In cases involving judgments, divorce settlements, or debt collection, knowing what assets a party actually holds is essential. Investigators conduct legal asset searches using public records — property filings, business registrations, court records, and similar sources — to help attorneys and their clients understand what may realistically be recoverable.

7. Interviewing Witnesses

A skilled investigator can approach potential witnesses, conduct informal interviews, and prepare detailed written reports of what those witnesses say. This information helps attorneys assess the strength of their case before depositions or trial, and can surface new leads that legal teams might otherwise miss.

What Attorneys and Clients Should Ask Before Hiring an Investigator

Whether you are an attorney evaluating an investigative firm or a client whose lawyer has suggested bringing one on, these are practical questions worth asking:

1. Are you licensed in this state? Licensing is required in most states. You can search for licensing requirements through your state's official licensing board or use USA.gov to find your state government's professional licensing portal.
2. Do you have experience with this type of case? Litigation support, domestic investigation, insurance defense, and criminal defense cases each call for different skills and experience.
3. How do you document your findings? Evidence must be gathered and preserved in a way that holds up in court. Ask about their reporting process and chain-of-custody procedures.
4. What are your fees and how are they billed? Reputable investigators provide clear, written fee agreements. Be cautious of anyone who guarantees a specific result — no honest investigator can promise what they will or will not find.
5. How will you keep my attorney informed? Investigators working on legal cases typically communicate directly with the attorney of record to protect privilege where applicable.

A Note on Attorney-Client Privilege

When an attorney retains a private investigator as part of case preparation, the work product generated may fall under attorney work-product protection in certain circumstances. This is a nuanced area of law, and the rules vary depending on jurisdiction and how the investigator is engaged. If you have questions about how investigative findings interact with privilege or discovery obligations, Nolo's legal guides offer accessible general information, but consulting a licensed attorney is strongly recommended for anything with direct legal consequences for your case.

When an Investigator Can Make the Difference

Attorneys work within strict procedural and ethical rules. A licensed private investigator, operating as a professional partner, can pursue avenues of inquiry that expand what a legal team knows before critical decisions are made — whether that is going to trial, accepting a settlement, or advising a client on risk. The investigator's role is not to win the case; it is to make sure the attorney has the most complete and accurate picture of the facts possible.

If you are working with an attorney on a matter that may benefit from professional investigative support, or if you are an attorney looking for a reliable investigative partner, Find A Local PI can connect you with a licensed private investigator in your area. Submit a request through this site at no cost and with no obligation — a professional will be in touch to discuss whether they can help with your specific situation.