The Federal Bureau of Political Investigation
Here is the back story.
The statutory obligation of the FBI is to gather evidence to aid in the prosecution or prevention of federal crimes or breaches of national security. The process of complying with this obligation necessarily involves making some legal judgments about the relevance, probity and even lawfulness of the gathered evidence. These judgments are sometimes made on the streets in an emergency and sometimes made after consultation and consensus. But the whole purpose of this evidence-gathering and decision-making is to present a package to the Department of Justice, for which the FBI works, for its determination about whether or not to seek a prosecution.