Crime involving computers costs $100 million to $300 million per year; the average computer-aided crime nets over $400,000. However, computer criminals are seldom apprehended becuase computer crimes are so difficult to prove. Other factors that help computer crime flourish include lax computer security, managerial disinterest in and ignorance of computers, poor personnel training, difficulty in distinguishing computer crime from computer error, and great potential gains. Types of computer crimes include unauthroized use of computer time, theft of information stored on a computer, embezzelment and other financial crimes, property crimes, and traditional crime such as kidnapping. Areas in which computers are vulnerable to tampering, in ascending order of technical difficulty, are input/output alteration, computer operations, computer programs, auxiliary storage manipulation, operating systems penetration, and interception and/or alteration of communications. Footnotes, tables, and figures are included.