UPDATE 5:45 p.m.:
— Julie Parker (@PGPDJulie) July 27, 2012
UPDATE 5:20 p.m.: Prince George's police post official blog entry. Highlights: ATF recovered 25 firearms. Suspect Neil Prescott remains under a doctor's care.
UPDATE: 3:44 p.m.: The search warrant (scroll down to read full document) for Prescott's home includes: "Prescott also stated that he would like to see the supervisor's brain splatter all over the sidewalk."
UPDATE: 1:50 p.m.: News4 sources say the complete reference to the Joker was something like "You don't know who the real Joker is. I am the real Joker."
UPDATE 1:30 p.m.: Breaking information in the case will be released first on the Prince George's County Police twitter feed.
UPDATE 1:15: Official speaking at the ongoing press conference: "A violent incident was avoided." Prescott has not been arrested or charged. He is in a medical facility.
UPDATE 1:10 p.m.: Prescott's call-in threat regarding a workplace rampage allegedly included the words "I'm gonna load my guns and blow everybody up."
When police made contact the suspect wore a T-shirt that said "Guns don't kill people, I do."
UPDATE 12:46 p.m.: The suspect has been identified as Neil Prescott, 28, of Crofton, Md., an employee facing termination at Pitney Bowes. Prescott called himself the "Joker" and a search of his home found "20 guns, including assault rifles and handguns, and more than 400 rounds of ammunition." Cops say Prescott called a co-worker, saying he wanted to shoot the boss. Authorities believe he was prepared to act on the threat.
The suspect was expecting to be fired from his job and had an arsenal of weapons in his home, authorities told the station. He had threatened his boss.
The man was busted in Crofton, Md., on Thursday. His name has not been released.
This isn't the first apparent copycat in the wake of the Colorado tragedy. Cops busted a man in Maine with a large weapons stash who said he had attended the Batman movie with a loaded gun.