Federal Bureau of Investigation
The Federal Bureau of Investigation (or FBI) is a US government agency responsible the primary role in investigation of federal crimes except for those crimes allocated to other agencies.
Relevant to computer forensics are the current Primary National Priorities include Counterintelligence, Counterterrorism and Cyber Crime FBI role in Cyber Crime.
Ongoing missions include Public Corruption, Civil rights, White Collar Crime, Organized Crime, and Major thefts and Violent Crime.
FBI and Cyber Crime
The FBI investigates computer intrusions (bots, malware, etc), predators, priacy and intellectual property theft, and internet fraud.
Disambiguation on the link FBI
Limitations on the FBI and collection of Computer Forensic Evidence
The FBI is limited by specific laws including the US Patriot Act,Communications Assistance for Law Enforcement Act (CALEA), and the Foreign Intelligence Surveillance Act of 1978 or FISA (USC 50).
Diffie and Landau : Privacy on the Line (2007) MIT Press