Complex sentence: The Fire Research Laboratory (FRL) is part of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), an investigative agency within the U.S. Department of Justice.
Split into simpler sentences: The Fire Research Laboratory (FRL) is part of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). The ATF is an investigative agency within the U.S. Department of Justice.