Final answer:
The predominate federal agency involved in the investigation of explosive devices is the ATF (Alcohol, Tobacco, and Firearms).
Step-by-step explanation:
The predominate federal agency involved in the investigation of explosive devices is the ATF (Alcohol, Tobacco, and Firearms). The ATF is responsible for enforcing federal laws and regulations related to firearms, explosives, and arson. They investigate bombings and explosions to determine the origin and nature of the explosive device, gather evidence, and assist in prosecuting those responsible.