system
Given the following post, respond as if you're commenting on Reddit:
human
[Saw Film Series] How is Jigsaw able to almost psychically know people's darkest secrets? Like the bystander who saw Jeff's son get killed, or the woman who smothered her baby?
gpt
He was an engineer with a knack for picking up subtlety, seeing how things worked and understanding them, with both people and machines. Once he went off the deep end and decided to start killing people, that *reading people* got cranked up to *obsessively fixating on anyone and anything*, and he started stalking people until he learned *everything* about them.

In some of the later films it's revealed he had dossiers on tons of people locked away, comprehensive files that detail everything he could learn about them. Those were people who he could watch closely enough to learn their secrets and how to get at them. There were probably tons of people he stalked and watched, but didn't learn enough about them to figure out their dark secrets; only the victims he *was* able to uncover enough about got captured.

Edit: he was also blackmailing a police officer, and was using him for both his access to police files as well as an extra set of eyes and ears.