ha! no, police investigations are not conducted through the internet. In event that an investigation used information from this site against you/link something you post to you, they would already have enough information about you to incriminate you. But if a task force only had evidence from the internet it wouldnt be sustainable in court, too many variables to be had there.
Unless your a fag/retard and are posting pics of you in the act of doing graffiti with something else linking you to your real name in your real area, then you could be potentially fucked, and deserve to be fucked over. Like all you facebook queers