Divorce cases can come from the public or from attorneys. Attorneys in small firms rarely keep investigators on payroll and will contract out investigative needs. If the attorney contacts you, he's your client and the one who will sign your client agreement. The complainant is his client. Be sure that this is understood so that everyone knows how — and by whom — your fees will be paid. Cultivate relationships with these attorneys and you'll have a steady stream of cases.

A private investigator will often be asked to provide proof that a spouse is cheating.

Many times, the client or attorney needs to prove that the target has been guilty of infidelity, is unfit to care for children, or is in possession of hidden assets. Some PIs won't work these cases; they feel it entails digging up dirt and they aren't comfortable doing it. Yet others make a career of it. If done right, it won't be a dirt-digging project, but a means of helping families in need. Not every case will end in divorce; sometimes people reconcile. If your client expresses the desire to work through her marriage, however, don't try to be her counselor; refer her to a licensed counselor or psychologist.

When working these cases, you'll attempt to obtain video on the target, documenting his comings and goings, associates, and possible infidelities. Gather as much information as you can beforehand. Obtain a picture of all players. Question the client as to the spouse's work, habits, hobbies, and interests. Get the make, model, tag number, and description of all vehicles. Perform a background check. Do a dry run by the spouse's home, workplace, and any areas he frequents (such as a bar, golf course, country club, and possible girlfriend's home and work).

Video is often the defining evidence in these cases. Because evidence is on screen for all to see, most he said/she said arguments are eliminated. To protect your evidence, use a new, clean tape or DVD every time. Never record over existing information or you may be accused of altering your video. This won't be an issue with the new digital recorders — just download the information to your computer and burn it to a clean, new disc or DVD.

While it's difficult to argue with video, some targets will say, “That looks like me, but it's not.” Let the attorneys deal with this problem, but you can help by obtaining corroborating witness information. Interviewing bartenders, hotel managers, even friends and coworkers after you have your video can substantiate video evidence. Witness testimony isn't easy to come by, but it is worth seeking. Although it is considered the least reliable type of evidence, a preponderance of witnesses testifying to the same information can sway jurors.