A District police officer was found guilty in a Prince George's County court yesterday of the second-degree murder of his brother, also a District police officer.

David Charles Jones, 33, who was convicted of an additional charge of using a dangerous weapon in the commission of a felony, shot his brother, Steven Paul Jones, 27, last May 2 during a heated argument in the living room of his home on Edgefield Drive in Adelphi, according to testimony during the trial.

Jones had pleaded not guilty by reason of insanity. Several witnesses in the trial, which was held without a jury before Circuit Judge James H. Taylor, said David Jones had suffered a serious drinking problem since his throat was slashed in 1975 while he was making an arrest.

According to testimony last week by Lawrence T. Roberts, who accompanied the victim to David Jones' house the night of the killing, the younger brother was berating Jones about his drinking. At one stage, Roberts testified, Steven Jones knocked David Jones down.

David Jones then pointed his .38-caliber service revolver at his brother and ordered him to kneel down, Roberts said. Steven Jones raised his fists in the air, according to Roberts' testimony, and David Jones fired three times. Two of the shots missed, but one hit Steven Jones in the heart. He was pronounced dead at the scene.

Both Steven and David Jones were uniformed officers assigned to the 2nd District in Northwest Washington. Their father, David Paul Jones, also served with the District police, retiring in 1980 with the rank of lieutenant. David Jones was suspended without pay after the shooting.