How Do Private Investigators work & How to Investigate Someone: From Taking a Case to Bringing it to a Close

A young female private investigator looking at her computer

A dark night in a city that knows how to keep its secrets. But on the 12th floor of the ACME building one man is still trying to find the answers to life’s most persistent questions. Guy Noir, private eye.

We all have our own preconceptions about what it’s like to be a private investigator, growing up watching stories and living the moments of suspense together with Sherlock Holmes, The Hardy Boys, Nancy Drew, and the likes of Guy Noir. But what is it really like to be a private eye?

What can you expect from the moment a client walks into your office until you’re both shaking hands and your client is thanking you for a job well done? But for that you need to know how do private investigators work, what their day-to-day life looks like, how to investigate someone or how to have someone investigated! Well, these are genuine questions which every aspiring detective must have but do not worry, we got your back.

This page will take you through some of the most common cases you’re likely to come across as a private investigator. You’ll be asked to solve plenty of mysteries during your career; understanding how cases progress doesn’t need to be one of them.

What is the investigative process going to look like from start to finish? That really depends on what kind of case you’ve got. We can start by making two broad distinctions. The types of work you’ll do will fit into one of these categories:

  • Cases involving the legal system
  • Cases involving client requests outside the legal system

Client Requests that Don’t Involve the Legal System

These types of assignments are usually initiated by private citizens and are not necessarily connected to the legal system. Examples of types of cases in this category include:

  • Missing persons – Your client could be looking for a long-lost friend, someone who owes them money, a runaway spouse, or their missing teenager who skipped town to live with her boyfriend.
  • Cases involving suspected infidelity – Your client may want confirmation for personal reasons that their spouse is having an affair. If your client wants you to gather evidence to present in court to justify a divorce filing, this means the case now involves the legal system.

When you have these types of assignments it’s important to have clear and direct communication with your client to know exactly what they want. As a good PI, you’ll give your client a straightforward and realistic assessment of how you can deliver, and what your client can expect.

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Even though these cases may not involve the legal system at first, it’s still a good idea to have a general understanding of applicable laws because it may ultimately end up in a courtroom.

Cases Involving the Legal System

These types of assignments involve conducting an investigation to gather evidence for presentation in a courtroom or other formal legal proceeding. When you start out as a PI these are likely the most common types of cases you’ll work. For these, it’s imperative that you understand the laws they apply to your case.

Examples of clients who deal with these types of cases are:

  • Law offices
  • Insurance companies
  • Government investigative agencies
  • Accountants
  • Businesses with a fraud or loss prevention department

Understanding how the law applies to these types of cases determines the level and quality of evidence you must obtain to be successful for your clients. It can also determine how you obtain this evidence.

Let’s illustrate this with an example. Say a client phones you up and says she is suspicious her husband is having an affair with his secretary during their lunch hour. Infidelity cases are one of the most common types of PIs. She wants you to gather evidence for use in court to file for divorce.

At this point, you check the law in your state about what evidence is needed to support a reasonable suspicion of infidelity. The law says that to have reasonable suspicion, the parties involved must fulfill all of the following conditions:

  • They must be at a location where they can commit the act
  • They must have a sufficient amount of time
  • They must incline – here this is a given because they’ve had a professional relationship at work for years

The law also says that a family court judge adjudicates divorce cases.

Now you can translate your understanding of the law into a successful plan of action. You tail the husband and secretary to a hotel on their lunch hour, snap a time-stamped photo of them going into their hotel room, and snap another time-stamped photo of them coming out of their hotel room 45 minutes later. Keep a logbook of their activities to supplement the photos. It’s as simple as that.

The strength in understanding applicable laws means you also know what you don’t have to do. This will save you a lot of time and effort and help you define the parameters of your investigation:

  • You don’t need to sneak around and take pictures through windows
  • You don’t need to install hidden video or audio devices
  • You don’t need physical evidence left behind by either the husband or secretary
  • You don’t need any statements from the secretary or husband
  • You don’t need to convince multiple people on a jury; the evidence you gather only needs to convince one judge

How do Private Investigators Work?

Thanks to all of the stereotypes of PIs that novels and TVs have created, some of them do paint a rather clear picture about investigative work but despite knowing all that you know from mere fiction, there is always a great wisdom attached to going into the depths of all that you are yearning to unravel. And whether you admit or not, we all have had this one prominent question of all times: how do private investigators work?

Separating fact from fiction, solving crimes, gathering evidence, surveilling, talking to witnesses, searching for records in various databases, evaluating clues, following trails and traces, connecting the dots and most of all  decoding every mystery that revolves around the case, you name it, private investigators do a whole deal and a lot more.

Solving the Most Common Cases from Start to Finish

These are examples of the most common cases PIs work with, and how they often play out from start to finish. In this section we’ll cover:

  • Child custody and visitation investigations
  • Serving papers
  • Internal investigations
  • Interviewing and questioning techniques
  • Stakeouts and surveillance
  • Tailing a target

So how do private investigators work? Let’s figure that out:

Child Custody and Visitation Investigations

These cases are huge for private investigators. You’ll almost always work with an attorney who hires you on behalf of their client. Lawyers are always involved because child custody and visitation hinges on complicated law. An attorney can tell you exactly what is needed to win a case in a courtroom.

The people you encounter will be those with a stake in a child custody legal dispute; fathers, mothers, grandparents, uncles, aunts, siblings, and so on. Because children are in the picture, the emotional involvement of all parties is going to be high. They are apt to tell you anything that makes their side look good and the other side look bad.

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Also, remember that ultimately the final report you make in this investigation is going to be presented in court. It’s true that you have a professional responsibility to your client. Though especially with cases involving children, many private investigators will remind you that you also have a professional responsibility to investigate and discover facts and the truth. Doing this allows the judge to make an informed decision on what is best for the children involved.

The attorney you’re working with is going to take care of conducting depositions of the key players involved. You can supplement this by conducting interviews with people like neighbors and grocery store clerks. Surveillance observations are also important.

These are the types of things that you look for and make a note of:

Competence and condition of your target

  • Evidence of illegal drug use or prescription drug abuse
  • Evidence of drinking or smoking
  • Evidence of healthy relationships or dysfunctional relationships
  • Is the target employed?
  • History of criminal behavior, or evidence of current criminal behavior

Environmental safety

  • Garbage or unsafe conditions in the child’s environment
  • Unstable or unsafe people in the child’s environment
  • Presence of child abuse or child neglect

The extent to which current legal guidelines are being followed

  • Are all parties adhering to the court’s previous or current orders?
  • Are all custody documents being followed?

Current well-being of the child

  • Interviews with teachers, coaches, religious community leaders, and child’s friends’ parents
  • Consideration of child’s academic performance
  • Stated preferences of the child

Child custody cases can involve the whole gamut of PI services, including everything from interviews with family members and friends to surveillance and stakeouts. These can take weeks or even several months to complete. You’ll ultimately compile your notes into a final report, and you may be called to testify.

Serving Papers

Also known as process serving, typically you’ll be hired by a lawyer, often a district attorney. Process serving involves finding a target person and physically handing them official legal documents. These could be anything from a court summons or subpoena to legal notification about something.

Needless to say, your target may try and actively avoid you. In fact, serving papers often begins as essentially a missing person case and your first goal is to actually track down your target.

Typically once you have located your target the next thing you must do is get them to confirm their name and a personal identifying feature about them, such as their date of birth, high school graduation year, or some other related detail.

How are you going to do this out of the blue with a complete stranger who is probably suspicious of your intentions? You lie.

Every PI has their own technique for this, including everything from creating fake sweepstakes to pretending to deliver a pizza.

For example, you could pretend to be a delivery person from a chocolate company. You arrive at your target’s door wearing a delivery outfit with a box of chocolates. When they answer you say you’re delivering chocolates because it’s their birthday, and make sure to confirm your target’s full name. When they say it’s not their birthday, you can look at a piece of paper and pretend to get your records mixed up, and then ask what date their actual birthday is. At that point, you hand them the legal papers, inform them they have been served, and get out of there.

Once you get back to the office you write up a report that details you confirmed the target’s name and date of birth, and that the papers were served. Send the report to the attorney who hired you along with an invoice. Mission accomplished.

Internal Investigation

Most large companies have internal investigation departments. If a store is consistently coming up short on products or cash during audits, or if it suspects employees are stealing time – clocking out early or taking long breaks – it will reach out to a private investigator.

When conducting an internal investigation, the first thing you’ll do is speak with the owner or main manager to establish exactly why they have hired you. Set their expectations for what you can deliver, and get to work on your investigation.

This could mean any of the following:

  • Interviewing many employees
  • Reviewing personnel records
  • Looking over old security camera footage
  • Computer forensics
  • Installing surveillance equipment

Your ultimate goal is to conduct a thorough investigation that sheds light on any wrongdoings. Go about your investigation with an eye towards gathering evidence that would support criminal or civil charges, should the employer decide to take any employees to court.

Usually, you can determine who your main suspects are by conducting good interviews with all the employees in the target department. If you can make a decent case against even one person, as skilled PI chances are you can make that employee squeal on the others.

Once you’ve gathered all your evidence and organized the relevant employee statements you’ll write up a final report for your client. This should include recommendations for avoiding employee problems in the future. Depending on how your client decides to proceed with your findings, you may be called upon later to testify in court.

The time you’ll spend on these types of cases varies on how many people you have to talk to. You can expect to wrap up an internal investigation after 80 to 120 hours of work.

It’s also common to be hired solely for the purpose of conducting in-depth background checks on potential employees.

Interviewing and Questioning Individuals

This is a big part of your work and you’ll eventually develop your own personalized techniques to open people up by gaining their trust and then getting the information you need.

Always bring a notepad and a recording device, and make sure that you explicitly have the subject’s consent – and maintain proof of this – to be recorded. Video cameras are better because they also convey body language.

Some people are talkers and that’s usually helpful. There are many methods to breaking the ice and gaining trust with someone you’re interviewing, and these usually involve establishing a common personal connection.

While you’re on safe and easy subjects you want to ask the subject questions that you already know the answer to, such as where they grew up, where they went to school, and so on. If you’ve been informed of specific neutral details about the subject – for example, they like the Red Sox because they knew someone who was a personal trainer for the team – ask them questions that will lead them to tell you this information. Pay attention to their body language and speech patterns as they do this. What you are doing is establishing what it looks like when this person is telling the truth.

Once you’ve established trust and a personal connection you can move on to the more difficult questions. If you feel you’re losing your subject’s trust you can move back to neutral topics to take some pressure off.

Since you know what your subject’s body language and responses are like when they’re telling the truth, you can also detect when they may be lying. This can help you shape the direction of your overall investigation.

Stakeouts and Surveillance

Young detective looking up close at a surveillance screen

If you’re a private eye you will definitely have this experience. Every example given up to this point could potentially involve watching a target for an extended period.

This is a good time to bring up another common type of case you may work on: those involving fraud. Especially insurance fraud and benefits fraud.

These cases involve people claiming insurance and government benefits, such as sick leave, disability benefits, and food stamps while faking their qualifications. In these cases, your clients will be insurance companies, employers, and government auditors or oversight departments. Conducting good surveillance for these types of cases is the main activity you will do.

Stakeouts are a waiting game, pitting you against your target and your patience. The number one rule of stakeouts: do not take your eyes off your target.

Conducting good surveillance involves extensive preparation. You’ll also need the basics:

  • Binoculars
  • Voice recorder to make notes
  • Paper pad and pen to make backup notes
  • Phone or radio to communicate with your team if you’re not doing the job solo
  • Camera or video camera
  • Wristwatch

Those are obvious. Here are some additional essentials that you might not think of:

  • Bring plenty of food with you – You cannot leave your post, even for five minutes for the drive-through. Ordering delivery is equally bad, as you may draw attention to yourself.
  • Get plenty of sleep before you start – How is it going to sound when you testify to the court that you were watching the subject for the entire night, except for the five minutes you dozed off?
  • When nature calls you’d better have a contingency plan already set up.
  • If you’re staking out your target from a car, be careful of using a cell phone or opening your car door if these give off light; keep your engine off because exhaust can be a giveaway so you’ll have to plan for cold or hot weather.
  • Keep extra cash on hand.
  • Smoking, like car exhaust, can also give you away; don’t do it.
  • Don’t do anything that distracts you even for a minute – reading, playing games on your phone, or even checking a different entrance; know where you’ve got to watch and stay there.

Most of the time you’ll conduct surveillance from a parked vehicle. When choosing a location to park, use your own best judgment. About five houses away should be sufficient. Keep in mind that neighbors or even police may approach your vehicle to check what’s going on. If this happens you want to be far enough away from your target to not be seen.

Remember the ultimate goal of a stakeout is to gather good evidence. This means taking solid notes and always marking them with time.

When your surveillance target makes contact with other unknown individuals make sure to note identifying details about each person.

Your mission is accomplished when you have the evidence you need, or you’re satisfied that you’ve made a thorough investigation and found a lack of evidence. Back at the office you’ll write a report and send it to your client. They will determine if further surveillance is necessary. You may be called to testify in court about what you’ve observed.

Depending on what’s needed, stakeouts can last anywhere from several hours to several days.

Tailing a Target

Statistically, this is one of the most dangerous activities you’ll do as a private detective. Not because you’ll be having rolling gun battles – that’s in the movies – but because driving is inherently dangerous, and you’re going to be doing this while you’re distracted looking at your target.

Following someone in your vehicle can be thought of as a type of surveillance. But you’ll need to modify your essential tools to be hands-free. This means:

  • Digital voice recorders with gigabytes of memory, or voice-activated recorders
  • Dash-mounted video camera
  • Bluetooth for your phone

The last thing you want is an accident right when you’re on a hot lead, so ensuring you can devote as much attention to driving is essential.

You’ll recognize you’ve got an obvious balance to keep: not letting your target get away, and not being too close to your target that you draw attention to. Here are some tips:

  • Wear clothing that matches your vehicle’s interior
  • Use a vehicle with tinted windows
  • Keep at least a few car lengths apart
  • Try to stay out of the target’s rearview mirror’s line of sight
  • If possible, scout out the route you’re going to drive ahead of time for anything like short stop lights or places where you have to make multiple lane changes quickly

There are variations on tailing someone too. If you live in a bigger city with a subway system or light rail you must plan ahead and buy the appropriate tickets in advance. You don’t want to get stuck in a line at a ticket vending machine as your subject gets away.

Ready to start your journey to become PI? Find private investigator schools, programs, and education options near you.


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