The NKVD was merely a continuation of the Okhrana, the Czar’s secret police.
Technically, the NKVD was a continuation of the Chekha, not the Okhrana. It’s the Chekha that was a continuation of that group (though that said, I’m not entirely sure it was a true continuation since Lenin apparently removed any and all restrictions from them, while even the Okhrana had some restraints placed upon them. Just ask Gary Saul Morson).