One of three suspects charged with hurling stones at motorists on the Capital Beltway and critically injuring a teenage girl has told police that he and his friends were drunk that night in celebration of his coming high school graduation, according to law enforcement sources.

Maurice Edward Ford, 18, of Oxon Hill, was arrested Saturday and gave "a full and complete statement detailing the incident," according to a police affidavit in his Prince George's County District Court file.

He also identified his two alleged accomplices, the affidavit states.

Police sources said Ford, who graduated from Oxon Hill High School the day before his arrest, told investigators that he and the others became drunk before the stone-throwing incident May 27. According to the sources, Ford told authorities he had not meant to harm anyone by throwing the stones.

Another youth, who said he was not involved in the incident, told investigators that he had been drinking wine coolers with the suspects, but declined their invitation to join in the stone-throwing, police sources said.

Witnesses said three young men hurled landscaping stones at the Beltway motorists near Livingston Road in Oxon Hill about 2:30 a.m. May 27. The stones, weighing 5 to 15 pounds, struck 27 vehicles, police said. One crashed through the windshield of a pickup truck carrying Destiny Morris, 15, of Hagerstown, Md., who remained comatose and in critical condition with a head injury yesterday at Southern Maryland Hospital Center in Clinton.

Ford's alleged accomplices, John Lavin Burgess, 18, of Forest Heights, and a 17-year-old juvenile, also were arrested Saturday.

There is no indication in Burgess's District Court file that he gave a statement to police about the rock throwing.

Ford and Burgess were charged with one count each of assault with intent to murder Morris, a felony punishable by up to 30 years in prison. Each was being held last night at the Prince George's County Correctional Center in lieu of $150,000 bail, authorities said.

Meanwhile, the Prince George's State's Attorney's Office said yesterday it will seek to prosecute the juvenile suspect as an adult.

Because the youth still is three months shy of his 18th birthday, authorities had no choice but to charge him initially as a juvenile and withhold his name from the public. But the chief of the state's attorney's juvenile unit yesterday filed a motion asking the juvenile court to waive its jurisdiction over the case and allow the youth to be prosecuted in Circuit Court on a charge of assault with intent to murder.

The juvenile's attorney, James S. Nickelsporn, said he had entered on behalf of his client a plea of "not involved," the equivalent of not guilty. He called the actions of the state's attorney "premature."

If the motion is denied and the youth's case is heard in juvenile court, he could be incarcerated in a youth facility until his 21st birthday.

The juvenile was being held last night at Boys' Village, a state facility for juveniles in Cheltenham, authorities said.

The chief of the juvenile prosecution unit, Jacqueline Bird-Tillman, said she decided to seek a waiver of the youth's case because of "the seriousness of the crime" and because the youth is nearing legal adulthood.

Under Maryland judicial rules, the nature of the crime and the defendant's age are two of five factors that the juvenile court must weigh in deciding whether to give up its jurisdiction over the case. The other three are the defendant's mental and physical condition, the danger he poses to society, and his amenability to treatment in counseling programs.

A date for a hearing on the waiver motion is expected to be set today.

The youth, who was not enrolled in school, was arrested at the Woodstock Job Corps Center in Baltimore. Burgess, who withdrew from Oxon Hill High School in January, was arrested at home, as was Ford.

A task force of Maryland State Police and county police questioned dozens of people before being led to the suspects.

The Stephanie Roper Committee, a victims' rights group, had offered a reward for information leading to the arrests and convictions in the Beltway case. But because no one volunteered information, the committee said, the reward fund of about $6,000 probably will be divided among those who were injured by the rocks, especially Destiny Morris.