It takes two heavily armed D.C. officers to protect a ledge from the likes of Jamie Loughner.

Loughner is the homeless advocate who occupied a fifth-floor ledge at the John A. Wilson Building for four days last winter.

The ledge, once on the outside of the building, was enclosed during a renovation that created a courtyard and outdoor walkway on each floor. Loughner scaled the seven-foot-high plate of protective glass separating the walkway railing from the ledge and crept along the ledge, 50 feet above the building's ground floor. Two weeks earlier, two other activists had done the same thing.

Officials said "enough'' to the disruption and publicity (never mind the fact that Loughner had relieved herself repeatedly on the ledge). After she left the ledge on Christmas Eve, the city installed two pieces of plywood that effectively raised the glass barrier.

They also assigned two officers from the D.C. Protective Services police to sit -- and sit and sit and sit -- and watch the hallway in case a potential ledge-dweller strikes again.

The police vigil has continued since December.

The officers read, they chat, they very occasionally rest their eyelids. But mostly they just watch. They don't see much. D.C. Council Chairman Linda W. Cropp (D) breezes by on the way to her office nearby; council member Adrian M. Fenty (D-Ward 4) fiddles with his BlackBerry. The officers also watch reporters shuffle in and out of the press room.

The silent sentinels would not comment on the record, citing department policy.

"It's an eight-hour job,'' said one.

But to the city it is a matter of security, according to Carol Mitten, director of the Office of Property Management, which oversees city buildings as well as the protective services force.

"It's not just preventing someone from getting out on the ledge. It's a safety issue,'' Mitten said. "Until we have those barriers adapted so no one could climb over them, we feel it's important in terms of protecting public safety to have our own security force guarding that area. That's a commitment that I made at the time."

She said the officers are not additional staff and ordinarily would have been deployed elsewhere in the building.

But why has it taken nearly nine months to order some pieces of glass?

Mitten said there was an error in ordering the panels, causing a delay in the installation.

Meanwhile, the city is relying on private guards from Hawk One Security Inc. to run X-ray machines and screen visitors at some building entrances. A Hawk One security guard who worked at another city building was arrested last month and charged with armed robbery. He was off-duty at the time of the alleged incident.

Mitten said the highly trained D.C. Protective Service officers, rather than private security guards, are stationed on the fifth floor because they would be better able to prevent someone from jumping the barrier.

Someone such as Jamie Loughner, who did not return a call seeking comment.