A Fairfax County jury deliberated 35 minutes yesterday before finding Thomas L. Grogg, 16, guilty of first-degree murder, robbery and use of a firearm in the shooting death of a Lorton construction worker who had given him and three companions a ride last October.

Commonwealth's Attorney Robert F. Horan maintained during the three-day trial in Fairfax County Circuit Court that Grogg killed Hallie Hollis, 28, for his money and car so that Grogg, his 19-year-old brother Robert and two others could get to Florida. Grogg was tried as an adult.

"This defendant and no one else put those nine bullets in the head of Hallie Hollis," Horan told the jury in closing arguments yesterday. Horan showed the jury on his own head the location of "each penetrating gunshot wound."

Grogg, of Fredericksburg, Va., had made a statement to police in which he admitted shooting Hollis. His attorneys argued that he should be found not guilty because he was intoxicated and was trying to protect his 16-year-old aunt from the Hollis' sexual advances.

Horan called that argument a "red herring."

He said the four were hitchhiking below Fredericksburg on Oct. 20 when they were picked up by Hollis, who lived in Williamston, N.C., and commuted to his job in Lorton each week. The prosecutor said the group made several stops for beer, wine and pizza and ended up at the Vulcan Materials Co. in Lorton, drinking and listening to the radio.

It was during one of their stops for beer, Horan said, that "Hallie Hollis' doom was well on the way to being fixed."

At that point, he said, that Robert Grogg told his younger brother that he "didn't like him [Hollis], his attitude and everything." The brothers later argued over who would kill Hollis, Horan said, and Thomas Grogg won.

Thomas Grogg testified that after he shot Hollis, the group went to a McDonald's restaurant and then headed for Florida.

The Grogg brothers and their two companions were arrested in Sarasota, Fla., after Hollis' car was found in Daytona. Robert Grogg pleaded guilty last week to first-degree murder in Hollis' death.

Each brother could be sentenced to a maximum of two life sentences.