A D.C. Superior Court jury convicted an 18-year-old city resident yesterday of stabbing his father and stepmother to death last September in the bedroom of their Northeast home.

The seven-woman and five-man jury, in a unanimous decision, found Monte C. Napoleon of 1106 Columbia Rd. NW guilty of two counts of second degree murder while armed in the slayings of Frank Napoleon, 53, and Katie Harrison, 66, at 1102 Florida Ave. NE on Sept 1.

Judge Sylvia Bacon ordered Napoleon, who was free on personal bond, to be taken to the city jail to await sentencing July 23.

The maximum sentence for each offense is life imprisonment.

Napoleon, who was the only defense witness, testified Friday that he killed his father and stepmother in self-defense after they attacked him during one of his weekly visits to collect his $10 allowance.

His father was in bed, Napoleon said, and as he sat at the foot of the bed, "I heard some strange noises behind me." He turned his head, he said, and when he turned back to his father, "Katie and my father attacked me."

Then, Napoleon testified, "Katie went under my father's pillow and came out with this butcher knife. After Katie got the knife, my father was still hitting one me."

Napoleon said he "knocked" his father off of him and then Harrison started toward him with the knife, but he forced it out of her hand and into a corner of the bedroom.

Napoleon said his father picked up the knife and as they struggled, he knocked the knife from his father's hand and retrieved it. "I started swinging," Napoleon said.

During cross-examination the defendant testified, "I hit my father first, then I swung and hit Katie. Both backed off, holding themselves. Then both came after me. I just kept on swinging. My last plunge was at Katie."

During the struggle, Napoleon said, his father said several times, '"I'll kill you,'" but after the attack, when he asked his father for an explanation, Napoleon said the older man did not reply.

Assistant U.S. Attorney E. Thomas Roberts said Napoleon was stabbed three times and Harrison five times.

Roberts argued that Harrison and Napoleon "had no background of violence" and were two hard-working people "who all through their lives showed affection for Monte Napoleon."

Defense attorney O. B. Parke said he had no comment on the verdict.

Napoleon's mother, Pearl Gough of 1106 Columbia Road NW, characterized her son as a quiet inarticulate man with a history of hospital treatments and examinations that never quite amounted to a diagnosis of a mental problem she believes he has.

"He went to the University of the District of Columbia to learn some kind of trade skill so he could get a job," Gough said. "But his teachers there said he had trouble sitting down and concentrating on his work and recommended he seek psychiatric help.

"He has gone to mental clincis around here, he's been treated at Children Hospital Center. But they said they couldn't find anything wrong with him. Once he went to Howard University Hospital and they treated him for seizures.

"He dropped out of Banneker Junior High in the 9th grade, and could not read or write too well. It was hard for him to understand things," she said. "He would sit at home and play with those teeny cars that kids play with, and I never understood that. He said he just like to play with them.

"I can't understand what could have happened that Friday when he went to see his father," his mother said. "He was crazy about his father. He was always saying Daddy is going to take me bowling, or Daddy is going to carry me to this place. He said his father and Katie promised to take him to lots of places, but they never did."