Neil Prescott, 28, of Crofton has been hospitalized and is undergoing treatment and evaluations for possible mental health problems, The Washington Post said. He has been charged with misuse of telephone facilities.
Prescott worked as a subcontractor the Capitol Heights branch of Pitney Bowes. Police arrested him last week.
Police said Prescott called his supervisor twice and threatened to shoot his employer, saying he was a "Joker." Officials said it was a reference to the mass shooting in Aurora, Colo., during a showing of "The Dark Knight Rises" in July, the Post said.
Prince George's County State's Attorney Angela Alsobrooks said Wednesday Prescott ought to be facing felony charges, but Maryland does not have a law that makes it "expressly illegal for a person to convey generalized threats over the telephone.".
The misdemeanor telephone charge carries up to three years in jail and a $500 fine.