Portrayals in various books, movies, and TV shows have all contributed to the stereotypical image of a private investigator as someone who works in a dimly-lit, often smoky office, solving criminal cases using a series of methods: taking photographs, scouring areas for clues others might have overlooked, questioning witnesses, and such. In the minds of many, the typical investigator wears a dark-colored trench coat and a fedora, and smokes a pipe.

Sound familiar? It’s fair to say that people often envision someone who conducts private investigations as reminiscent of the iconic character Sherlock Holmes. While certain investigative methods perpetuated by characters like Holmes do bear a resemblance with today’s real-life detectives, in truth, the two entities differ greatly. Here’s how.

Characters like Holmes (or for more a more contemporary example, Veronica Mars), typically get into legal trouble for their rather quirky investigative tactics. Real-life investigators from firms like Phenix Investigations, Inc. do not. They work within the boundaries of the law at all times, and like police officers, they can’t present evidence which wasn’t legally obtained. For instance, in the Veronica Mars movie, the title character trespassed into a murder suspect’s house to obtain information, which led to her arrest. Real world private eyes of today cannot enter a property through illegal means, and they typically require the permission of the owner before entering.

Private investigators (or PIs) also assist lawyers in preparing for court cases, working from either side, though PIs are almost always working for the defense. Typical PI tasks include locating case participants, performing documentation of suspected crime scenes, and interviewing witnesses—in other words, PIs do anything to help in looking or presenting evidences and witnesses as may be needed in a case, which can range from workplace investigations, insurance fraud, and child custody and divorce cases, to criminal cases like theft and murder.

For someone to legally render private investigator services, a licensure process is typically mandatory. To date, 46 states require PIs to satisfy the requirements of a state licensure process. The process can have specific requirements, including (but not limited to) education and experience, standard application, and renewal. A select number of states even allow PIs to carry weapons and thus require firearms training and certification, as well as certification renewal. For all the things PIs can do, however, they can’t make legal arrests—all they can perform is a citizen’s arrest, depending on the situation. In other words, you can’t expect a PI to subdue a suspected criminal like a police officer would.