Hiring a private investigator isn't like booking a hotel room — the wrong choice can waste thousands of dollars and compromise your case. Knowing exactly what to look for before you sign anything separates a successful investigation from a costly dead end.
Verify Licensing Before Anything Else
Every state requires PIs to hold a valid license, and this is non-negotiable. Ask for the license number and verify it directly through your state's licensing board website — don't just take a photo of a certificate. Some investigators work under a supervising agency's license, which is legal in many states, but you should still confirm the arrangement is legitimate.
Red flags to watch for:
- Refuses to provide a license number upfront
- Lists only a PO box with no physical office address
- Claims licensing "isn't required in your situation"
- Has no verifiable professional history online
Understand What Type of Investigator You Need
Private investigation is a broad field. A PI who specializes in corporate fraud isn't necessarily the right fit for a child custody case, and someone who excels at background checks may have zero surveillance experience. Be specific about your situation when you call.
Common specialties include:
- Surveillance — tracking a person's movements, documenting behavior
- Background investigations — employment history, criminal records, financial checks
- Infidelity investigations — discreet documentation for personal or legal use
- Missing persons — locating people through legal database searches and fieldwork
- Insurance fraud — gathering evidence of fraudulent claims for insurers or attorneys
- Corporate intelligence — due diligence, competitive research, employee misconduct
Ask the Right Questions During the Consultation
Most reputable PIs offer a free initial consultation. Use that time carefully. Vague answers to direct questions are a major warning sign.
Good questions to ask:
- How many cases like mine have you handled in the last 12 months?
- Will you handle my case personally, or assign it to someone else?
- What methods will you use, and are they all legal in this jurisdiction?
- How do you structure fees — hourly, flat rate, or retainer?
- What happens if you don't find anything?
- Will you provide written reports and photographic or video evidence?
A PI unwilling to explain their methods clearly is one you should walk away from.
Know What Realistic Costs Look Like
Private investigator fees vary significantly based on location, complexity, and the investigator's experience level. Hourly rates typically fall between $75 and $200 per hour, with experienced PIs in major metro areas charging at the higher end. Surveillance cases often require a minimum of 4–8 hours per session to produce meaningful results.
Many PIs require an upfront retainer — commonly $500 to $2,000 — which is drawn down as hours are worked. Get a clear written breakdown of what that retainer covers before you pay it. Ask whether unused retainer funds are refundable.
Be skeptical of anyone quoting unusually low rates. A PI charging $35 an hour is likely cutting corners somewhere — legally or ethically.
Confirm They Operate Within Legal Boundaries
A reputable PI will never tap phones, hack accounts, access private records illegally, or trespass on private property. These actions not only invalidate the evidence in court — they can expose you to legal liability too. Ask directly what databases they use and how they access them. Licensed investigators have legal access to tools like LexisNexis, IRB Search, and TLO, which are unavailable to the general public.
Avoid anyone who promises to get information "off the books" or implies they have insider contacts at law enforcement who will pull records for them.
Review the Contract Carefully
Before signing anything, read the agreement line by line. A solid PI contract should clearly specify:
- Scope of work and defined objectives
- Hourly rate or flat fee structure
- Retainer amount and refund policy
- Estimated timeframe for the investigation
- How and when reports will be delivered
- Confidentiality obligations
If the contract is vague or one-sided, ask for revisions. A legitimate investigator will have no problem clarifying terms.
Check Reviews and Professional Affiliations
Look for memberships in organizations like the National Association of Legal Investigators (NALI), ASIS International, or your state's PI association. These aren't guarantees of quality, but they indicate the investigator takes the profession seriously.
Read Google and BBB reviews with context — one or two bad reviews among dozens of positive ones is normal. A pattern of complaints about billing, communication, or results is a serious concern.
If you're not sure where to start your search, Mercoly makes it easy to compare and find trusted private investigator providers in one place, so you can evaluate credentials, specialties, and reviews side by side.
Start with a clear goal, ask hard questions, and verify everything in writing before your investigation begins.