“Hanssen was caught not by superior investigative skill, but by purchasing insider information from a former KGB officer” The examples of the most successful and unsuccessful criminal and the counterintelligence investigations: comparisons, analysis of factors of success or failure, conclusions – Google Search https://www.google.com/search?q=The+examples+of+the+most+successful+and+unsuccessful+criminal+and+the+counterintelligence+investigations%3A+comparisons%2C+analysis+of+factors+of+success+or+failure%2C+conclusions&newwindow=1&sca_esv=e11ce942ef99a1b2&cs=0&hl=en-US&aep=1&prmd=ivns&sxsrf=ANbL-n4WbwRwjUP9-A12B1ErSCchrsZNVA%3A1777654519738&source=lnms&fbs=ADc_l-aN0CWEZBOHjofHoaMMDiKpaEWjvZ2P