A man who crashed an 18-wheel tractor-trailer into the Washington Monument last November pleaded guilty in D.C. Superior Court yesterday to destruction of government property.

Garrow E. Brigham stood silently as a federal prosecutor described how the truck driven by the 37-year-old Laurel man veered off Constitution Ave., charged up the grassy approach to the monument and plowed through snow fences and flag poles before crashing into the structure. The Nov. 20 incident happened shortly before the Monument was scheduled to open.

Prosecutor Barbara Van Gelder told a D.C. Superior Court judge that when a National Park Service employe approached Brigham, who was standing beside his truck, Brigham handed the employe a number of items he was holding, including a pair of scissors and a magazine photograph of a diamond ring.

Van Gelder said that Brigham told the park worker: "I want those in my office in five minutes." She said that when the employe asked where the office was, Brigham pointed to the top of the monument and said, "Right up there."

Van Gelder said that Brigham appeared to be under severe mental stress at the time and was taking pain medication for an elbow injury.

She told the judge that the government had accepted Brigham's plea and agreed not to ask that he be incarcerated pending sentencing, on condition that Brigham not seek a drivers' license in the District, Virginia or Maryland.

Van Gelder added that Brigham has made restitution for the $3,500 damage he had done to the monument.

Brigham could be sentenced to up to 10 years in prison and fined up to $5,000.