WASHINGTON – To his friends, Neil E. Prescott was a "gentle giant" – a physically towering young man with a background in computers and electronics and a sarcastic, even biting, sense of humor that people close to him knew to shrug off as innocuous.

But police say they had no choice but to take it seriously when Prescott threatened to shoot up his workplace and referred to himself as "a joker," comments that raised particular alarm in the wake of last week's mass shooting at a Colorado theater during the latest Batman movie. The man accused in the Colorado shootings dyed his hair reddish-orange, and New York Police Commissioner Ray Kelly has said the man called himself the Joker – a reference to Batman's nemesis.

Prescott was taken into custody early Friday at his apartment in Maryland, where officers found several thousand rounds of ammunition and a cache of about two dozen weapons including semi-automatic rifles and pistols. He was receiving an emergency psychiatric evaluation at a hospital and had not been charged as of Saturday afternoon.