One of the disadvantages of private investigator work is the irregular hours that it requires. This is due to the fact that most of the cases that they handle require surveillance and interviews with people who might not be available during normal working hours. Aside from doing surveillance operations in different locations, a private investigator may also spend most of his working hours inside his office making computer searches and making phone calls to people who might be able to help him with his case. Private investigation is also not without its share of danger. In fact, some private investigators are licensed to carry firearms or handguns.