A 15-year-old Landover youth was arrested yesterday and charged with fatally beating an Army recruit at a Largo mall this month, Prince George's County police said.

Authorities would reveal no motive in the slaying of Matthew Pickett, 21, who was attacked Nov. 5 outside the Boulevard at the Capital Centre. Pickett, who lived in Upper Marlboro and worked as a teacher's aide, died two days later.

Police charged the youth, who was not identified, as a juvenile with manslaughter, said Cpl. Diane Richardson, a police spokeswoman. Officials declined to release further details.

Pickett's relatives were upset by the juvenile manslaughter charges, the victim's uncle, Mark Pickett, said in a telephone interview last night.

"It's a complete travesty if this kid gets manslaughter at 15," Pickett said. "We feel he should be charged as an adult because he's doing adult things."

Investigators received many tips that helped identify the youth who was charged, Richardson said.

Pickett and his girlfriend were heading to the movie "Jarhead" when the beating occurred. Police said in earlier reports that he was struck on the back of the head with a metal pipe.

Police investigators told the victim's family that they now think the teenager and Pickett might have bumped into each other, with the teenager then throwing a punch, Mark Pickett said. Police theorized that the fatal injury occurred when Pickett hit the ground, his uncle said.

Family members are skeptical of that theory and pointed out that police said initially that a group of youths might have played a role in the attack. Other witnesses told the family a similar account, Mark Pickett said.

Matthew Pickett, a son of an Army Ranger, was awaiting the start of basic training next month at Fort Benning, Ga.