The second of three Alexandria youths to be sentenced for the Jan. 2 slaying of Federal Trade Commission economist Stephen Marston and the wounding of his wife in their Parkfairfax home was ordered yesterday to serve life plus 80 years in prison.

Jeffrey D. Harris, 17, who was tried as an adult, pleaded guilty to first degree murder, felonious assault, burglary, two counts of robbery and three firearms charges. He was silent as he was sentenced by Alexandria Circuit Judge Donald H. Kent. He will be eligible for parole consideration in 15 years.

Harris' attorney, Stephen R. Prickard, told Kent that his client was "deeply remorseful."

According to court testimony, Harris and brothers Boggess Steve Davis, 20, and Bartel Davis, 17, of 421 N. Payne St., went to the Marstons' Parkfairfax neighborhood last Jan. 2 looking for a "hustle."

According to earlier court testimony, Boggess Davis robbed Marston, 36, at gunpoint in the front yard of his home at 3606 Greenway Place about 9 p.m. while Harris and the younger Davis ran into the house and began to rob Marston's wife, Martha F. Riche, and burglarize the house.

Marston was shot to death and Riche, 43, was wounded in the chest.

Boggess Davis was sentenced last month to two life sentences plus 62 years. Bartel Davis, charged as an adult, also has pleaded guilty to the murder, assault robbery, burglary and firearms charges and is scheduled to be sentenced Aug. 25.