Law enforcement agencies keep investigative information close - often down to the investigative team, doling it out in small packets on a strict 'need to know' basis (with the team judging who needs to know). This is a major block to effective intelligence work, but they are all paranoid about leaks, and well aware that higher-ups will leak for publicity, fellow officers jump on their turf and others are connected to the targets. The FBI follows this pattern. The CIA, as part of the intelligence community, does not trust law enforcement, for all these reasons, and shares on a selective need to know. It does cooperate with the rest of the intelligence community, at least on the gathering side (less so on operations).

They do run joint clearing centres, with wide access, but these again have issues with dissemination. Basically, there's no single standard for clearance, little coordination and a lot of mutual mistrust.