A U.S. Coast Guard lieutenant was arraigned Monday on gun and drug charges in a case authorities say linked him to a plot to killed several prominent Democrats and broadcast journalists.

Christopher Hasson, 49, pleaded not guilty to charges of illegal possession of firearm silencers, possession of firearms by a drug addict and unlawful user, and possession of a controlled substance.

Hasson was arrested last month in the parking lot of the Coast Guard headquarters where he had worked for three years. A search of his Silver Spring, Md., apartment turned up 15 firearms, including seven rifles, and over 1,000 rounds of ammunition.

Read more: NPR