A former software executive's guilty plea to charges of breaking into a rival's computers and <A HREF="http://news.zdnet.com/2100-1009_22-5989750.html?tag=zdnn.alert">stealing trade secrets</A> has offered a rare glimpse into the world of corporate espionage. John O'Neil, former CEO of Business Engine Software, pleaded guilty in a San Francisco federal court on Wednesday to conspiracy to download and steal the trade secrets of software competitor Niku over a 10-month period. O'Neil, 43, is the third former executive of the San Francisco company to admit guilt in a case that the FBI's computer intrusion squad helped to investigate in 2002. He faces a maximum sentence of 10 years in jail and a $250,000 fine. Sentencing is scheduled for next spring.