There is not only collaboration among police/security agencies within the US as reported here: this article exposes the collaboration of the Empire's militarized polices across the globe, particularly influenced by the Israeli model.
The Israelification of America’s security apparatus, recently unleashed in full force against the Occupy Wall Street Movement, has taken place at every level of law enforcement, and in areas that have yet to be exposed. The phenomenon has been documented in bits and pieces, through occasional news reports that typically highlight Israel’s national security prowess without examining the problematic nature of working with a country accused of grave human rights abuses. But it has never been the subject of a national discussion. And collaboration between American and Israeli cops is just the tip of the iceberg.