Final answer:
The FBI is the main agency to help investigate gangs and their activity, especially within the U.S. national borders, whereas the DEA can also play a role in cases involving drug trafficking. State-level agencies like GIITEM may also be involved in gang investigations.
Step-by-step explanation:
The agency that could help you investigate gangs and their activity is the Federal Bureau of Investigation (FBI). The FBI is the chief federal law enforcement agency within the United States and focuses on a multitude of criminal activities, including organized crime and gang activities. The FBI's efforts are governed by constitutional protections, such as the Fourth Amendment, but they have a range of tools at their disposal for combating gang-related crimes. For instance, the FBI's Uniform Crime Reports and Hate Crime Statistics can provide valuable insights into criminal activities associated with gangs.
The Drug Enforcement Administration (DEA) is another federal agency that may be involved in investigating gangs, especially those engaged in drug trafficking. However, their primary focus is on combating drug smuggling and drug abuse within the United States. The DEA's website also offers resources and a tip hotline that could be useful in a gang investigation that involves drugs.
On a state level, organizations like the Gang and Immigration Intelligence Team Enforcement Mission (GIITEM) may also be involved in investigating gang activities, specifically in the state of Arizona, where it operates. While not a federal agency like the FBI or DEA, GIITEM plays a crucial role in local and state-level enforcement against gangs.