An Alexandria judge, after hearing testimony from the wife of a government economist slain Jan. 2, ordered yesterday that a grand jury consider whether Boggess Steve Davis should be tried on burglary and robbery charges.

Following the 90-minute preliminary hearing in General District Court, Commonwealth's Attorney John E. Kloch said he also will ask the grand jury, which meets Monday, to add murder to the charges against Davis.

Davis, 20, and two juveniles, are suspects in the robbery-related killing of Steven Marston and the shooting of his wife, Martha F. Riche in their rented town house at 3603 Greenway Place in the Parkfairfax section of Alexandria.

One of the juveniles, a 16-year-old, is charged with firing the shots that killed Marston, 36, and wounded Riche, 44, in her upper chest.

Riche, in 30 minutes of emotional testimony, told Judge Robert T.S. Colby that the night of the killing she and her husband were hurrying back to their home to watch a TV program at 9 p.m. She said she saw three youths walking in the neighborhood and remarked to her husband that they were "up to no good."

As the couple unloaded boxes from their car in preparation for moving to a new home in Arlington, she said she was startled to see two of the youths poke their heads into the living room.

"I think I was paralyzed," said Riche. She said she could not understand what the youths said and directed them to her husband who was still outside. Three youths returned. One held her husband's arm with one hand and had the other stuck in his back, she testified.

For the next eight to nine minutes, she said, the youths repeatedly demanded money. She said they took her purse, containing $100, and a camera and flash unit from nearby tables. The entire time, she and her husband stood facing each other at the foot of a staircase, she said.

"One of them [the youths] said turn out the lights," she recalled. And breaking into tears she said: "Then they shot my husband in the back and then they shot me."

"I saw my husband die," Riche said. The youths ran away and Riche ran into the street screaming for help. Riche identified Davis as one of the youths involved in the incident.

A 17-year-old girl, who said she was in a parked car Davis had driven to the Parkfairfax neighborhood the night of the shootings, also testified. She said Davis and the youths returned to the car with a gun and a woman's purse about 15 minutes after they had arrived near Marston's home.

Davis, of 421 N. Payne St., is being held without bond.