From identity theft to bogus stock sales to counterfeit prescription drugs, crime is rife on the Web. But what has become the Wild West for cybercriminals has also developed into a major business opportunity for cybersleuths.

One of the most well-known is Kroll Ontrack, a technology services provider that Kroll, an international security company based in New York, set up in 1985. Others include ICG Inc. in Princeton, N.J.; Decision Strategies in Falls Church, Va.; and Cyveillance in Arlington, Va., all started in 1997.

"As more and more crime is committed on the Internet, there will be growth of these services," said Rich Mogull, research director of information security and risk at Gartner Inc., a technology-market research firm in Stamford, Conn.

ICG, for example, has grown to 35 employees and revenue of a projected $7 million this year from 8 employees and $1.5 million four years ago, said Michael Allison, its founder and chief executive.

ICG, which is a licensed private investigator, tracks down online troublemakers for major corporations around the world, including spammers and disgruntled former employees as well as scam artists, using both technology and more traditional cat-and-mouse tactics.