Seven-year-old David Sutton was sweeping off the balcony of his Silver Spring apartment late one afternoon last August when he saw two men, who were "walking very suspiciously," approach his building.

"I ran inside and grabbed my father's binoculars." he recalled. "I wanted to see if they had a weapon in the bag they had with them. That way my Mom would be sure to call the police; she could be sure they weren't just getting exercise."

They weren't. As David watched through the binoculars from his bedroom window, the two men [WORD ILLEGIBLE] an elderly neighbor of David, held a bayonet to his stomach, and took $37 from him.

Three months later, David was shown a series of photographs by police. He picked out the photograph of Arthur Drake Martin, 23, and identified him as one of the two robbers.

Yesterday Martin, an ex-Marine, chose to enter a plea of guilty to a charge of robbery rather than face a trial on a more serious charge of armed robbery. It was a decision based in part on the fact that a suspicious 7-year-old with binoculars who had seen the entire robbery would be one of the chief witnesses against him, according to his attorney.

"I didn't really look forward to testifying," David said recently, "but a few months after [the mug shot identification] we got a papare saying I had to go to court."

So, three weeks agon, when the case was first scheduled to be heard he went and sat down anxiously in the Montgomery County courtroom next to Assistant State's Attorney Judy Catterton, who was to try the case.

"Will I have to sit in the truth chair?" David whispered to Mrs. Catterton. "You know, that chair there next to the judge where you have to tell the truth?"

Mrs. Catterton assured him that he would - but that was before she held a private conference with defense attorney Wood and the guilty plea was agreed on.

Though Martin may disagree, as far as David is concerned the whole episode has turned out grandly. "I'm proud of myself," he said.