Third Section
The Third Section was set up in 1826 and was designed to combat corruption and champion justice. It was headed up first by Count Benckendorff and then Aleksey Orlov. The former hoped it would be something of a 'moral physician' to the people; an organisation they trusted and respected. In the beginning, the 'blue archangels' (so called because of their blue and white uniforms) fulfilled this hope--they proved themselves far more efficient at maintaining law and order than the ordinary police.
However, over time its reputation deteriorated as it became progressively easier to imprison than investigate. The Third Section became associated primarily with the suppression of any liberal ideas as well as strict censorship. Although only three periodicals were ever banned outright, most were severely edited.
The Third Section also worked in close conjunction with the fourth section, which dealt with education. Both were keen to repress 'dangerous' western liberal ideas, such as constitutional monarchy or even republicanism. Throughout Nicholas' reign, thousands of students were kept under strict surveillance.
The Third Section could imprison or exile anyone to Siberia without trial. Bribery was commonplace, resulting in many innocent people being arrested.
In short, the Third Section formed the real roots of the KGB.