The median annual wage of private detectives and investigators was $42,870 in May 2010. The median wage is the wage at which half the workers in an occupation earned more than that amount and half earned less. The lowest 10 percent earned less than $25,760, and the top 10 percent earned more than $74,970.
Private detectives and investigators often work irregular hours because they need to conduct surveillance and to contact people outside of normal work hours. They may work early mornings, evenings, weekends, and holidays. In addition, they may have to work outdoors, or from a vehicle, in all kinds of weather.
Source: Bureau of Labor Statistics, U.S. Department of Labor, Occupational Outlook Handbook, 2012-13 Edition