Katsav was caught because (1) He committed too many crimes and left too many witnesses. (2) The witnesses persevered through many difficulties. (3) His story didn't pass the laugh test. As we have seen Sharon (and his family) were crooks, Olmert was a crook, and Lieberman is a crook. Israels politics and society are as corrupt as can be. The ones who are caught are the most stupid or arrogant. Any smart Israeli crooks stay below the media radar.
Palestinians report IDF airstrikes on Islamic Jihad targets in southern Gaza Strip (Haaretz)
from the article: Katsav's lawyers: We'll appeal 'unequivocal' rape verdict