A 15-year-old Manassas boy -- reported missing Saturday night after he failed to return from riding his dirt bike in a remote area of Woodbridge -- was found dead yesterday afternoon, and a Stafford County man was charged with murder last night in connection with the death.

The body of Alexander "Alex" Eugene Sztanko was found by a Spotsylvania County sheriff's deputy assisting Prince William County police about 2:30 p.m. in a wooded area between Interstate 95 and Highway 234 near Beau Ridge Estates. The boy was found about one-half mile from the house where he had begun his ride.

Police would not comment on the cause of death, but said an autopsy will be performed today.

Late last night, Michael George, 32, of Hartwood, Va., was charged with murder in connection with the killing. He was ordered held without bail.

George pleaded guilty in 1984 to charges of involuntary manslaughter and abduction in the disappearance of 8-year-old Larry Perry of Dumfries five years earlier. He had been charged with murder in that case after telling investigators that he had taken the boy into the woods in southeast Prince William County, where he said the child accidentally shot himself with George's gun.

His attorney said at the time of his guilty plea that George had panicked and buried the body, which was never found.

George was sentenced to five years in prison for the killing. During a preliminary arraignment last night, he told a Prince William County magistrate that he had served 2 1/2 years in prison on the charges.

Prince William County police Sgt. Barry Barnard said George was arrested for trespassing yesterday afternoon in the area near where Alex's body was found. The murder charge was filed after George was questioned at the Gar-Field county police substation, Barnard said.

Authorities identified George as a civilian computer operator with the Marine Corps Exchange Service.

Barnard said there was no indication that the suspect knew the youth. The dirt bike on which Alex was riding, a Kawasaki KX80, has not been found, he said.

More than 75 searchers -- including Prince William police and officers from surrounding county agencies -- had begun the search for Alex at first light yesterday.

He was last seen about 2 p.m. Saturday at the family's former house in the 15400 block of Cardinal Drive, the boy's mother, Gail Sztanko, said while waiting for the searchers.

The family was at the house packing items to complete their move to Manassas, where they relocated in November, she said.

Police and residents characterized the neighborhood of single-family houses as safe and said there had been no reports of unusual people or threatening activity.

Gail Sztanko said her son, who had just completed ninth grade at Potomac High School, was usually not permitted to ride alone, but she had allowed him to leave to try to catch up with three of his friends who had taken off about an hour earlier.

"He was supposed to ride with them, but he was late because he was mowing his grandmother's grass," Sztanko said. "We don't usually let him ride alone, but he said he could catch his friends. He really wanted to go so we let him," she said, fighting back tears.

He had promised to return by 7 p.m., and the family notified police at 8 p.m. that he was missing. Family friends began a search Saturday night, but turned up nothing.

Police officials, aided by two helicopters and a volunteer canine unit, joined the search yesterday. Friends and relatives of the family converged in the area to assist.

They remembered Alex as a well-adjusted teenager who was a member of the choir at St. Paul's United Methodist Church of Woodbridge, a good student and very close to his family. Besides dirt biking, which friends called his obsession, he also enjoyed bowling and pool. He was on a member of his school soccer team. he was missing when it was announced in church. "I feel any help I can give my family would be good," she said. "I just want to do my part to get out there and find Alex."END NOTES

After police announced they had found the body, family and friends gathered at the scene turned to each other for comfort in their grief.

Fifteen-year-old Roy Berry, one of Alex's best friends and a dirt biking partner, sobbed in his mother's arms. "He's the best rider in the world. A real nice guy," Roy said.