An aide to Sen. Barbara Boxer was arrested Tuesday after trying to bring marijuana into the Hart Senate Office Building, according to a Capitol Police report.

Marcus M. Stanley, who was senior economic adviser to the California Democrat since 2009, was observed trying to “remove and conceal” a “green leafy substance” from his pocket during a security screening at the building’s Constitution Avenue door, according to the report.

Stanley was arrested after a field test determined the substance to be marijuana. He has since resigned.

“Marcus Stanley is no longer with this office,” Boxer spokesman Zachary Coile said. “He submitted his resignation and Senator Boxer accepted it because his actions yesterday were wrong and unacceptable.”

Before joining Boxer’s office, Stanley was a senior economist for the Joint Economic Committee starting in 2007, according to Legistorm. He has also worked for the Senate Environment and Public Works Committee, which Boxer chairs.