Stephen M.J. O'Donnell, a thin, bespectacled 15-year-old who often was the butt of jokes, was mourned by his teen-aged acquaintances yesterday as a victim of his craving for attention and acceptance.

O'Donnell, his schoolmates said, probably didn't realize what he was doing when he suggested to some new friends that he drink "hard liquor" rather than the beer they had suggested as an initiation rite into "membership" in a makeshift fort near Ft. Belvoir.

Precisely what killed O'Donnell, whose body was found Tuesday under the shrubbery of a neighbor's house south of Alexandria, remained unknown last night. He appeared, however, to be the latest victim of what police and educators agree is an alarming upsurge in problem drinking among American teen-agers.

According to those who knew him best, it was probably the hope of acceptance more than a love for alcohol that killed O'Donnell."He just wanted to fit in," said Teresa White, a 16-year-old whose face was twisted yesterday by the shock of O'Donnell's death.

"It's the damnest thing I've ever seen," said police investigator Phil Grimes yesterday as he and other detectives attempted to retrace how O'Donnell met his death in a modest suburban neighborhood where he had lived less than a month.

Friends of the youth, the son of C. J. O'Donnell, a career Coast Guard enlisted man and his wife, said O'Donnell's days at two high schools in the county were filled with efforts to win the aclaim and attention of his peers. Once O'Donnell joined an all-girls, 20-member "pep squad" to, according to a friend, "get my picture taken with all the girls for the school year book."

Almost unfailingly O'Donnell's efforts never seemed to succeed.

With his hair cut short and wearing thick glasses, O'Donnell seemed to stand apart from his teen-aged peers. Unlike many of them, he could not shake off their often crude and sarcastic humor. "He had a very hard time taking it . . . they made sport of him," said Karen Boettcher, whose Coast Guard husband was the adult sponsor of a teen-age club at the Mount Vernon Square apartment complex off Richmond highway where the O'Donnells lived for nearly seven years.

Worried by a shooting incident at the nearby Groveton High School, the O'Donnells moved recently to a green shingled home at 4910 Sprayer Ct. on a small cul-de-sac in the Woodlawn subdivision about five miles south of Mount Vernon Square.

It was there on Friday, a school Thanksgiving holiday, that O'Donnell set out again to attempt to make new friends. Leaving his home, O'Donnell set off with two 15-year-old neighborhood youths to what police said was a "makeshift fort" about a mile-and-a-half way in a wooded grove on the Ft. Belvoir army post. O'Donnell rejected their suggestions for an initiation rite" including a beer-drinking stunt that police said was taken from the television show "Happy Days"

Later when the boys returned to the neighbor's home, O'Donnell said he "wanted to drink hard liquor," according to the police report. The neighbor boys obliged.

As a 13-year-old brother of one of the 15-year-old youths poured liquor from their father's basement bar, O'Donnell downed "several 8-ounce glasses, filled alternately with vodka, grenadine or scotch, police said. "As far as I can tell it was his (O'Donnel's idea," Grimes said. But after three hours O'Donnell passed out and the two brothers who lived in the house where the drinking occurred tried to revive O'Donnell by placing him in the shower. When this failed they panicked, according to police.

Reacting to "fear . . . fear of anything; their parents, the police," the boys wrapped O'Donnell's body in a blanket and carried him to a wooden 'barnlike' storage shed behind their house and left his body there until the pre-dawn hours Monday morning. Grimes said yesterday that police probably will not know until they receive a toxicology report today precisely when O'Donnell died or what killed him. He could have died from either alcohol or exposure.

A police statement said the boys checked on O'Donnell "periodically" until about 9:30 p.m. Friday when he was seen alive but unconscious. The boys have told the police that when they checked on him Saturday morning between 7 to 9 a.m. they found him dead. His body was left in the shed until the pre-dawn hours. Modday morning. Then they carried it across the street from their home and hid it under shrubbery on the side of a neighbor's house. Police discovered the body there Tuesday night after becalled to the scene by authorities at Mount Vernon High School.

Fairfax County authorities said the incident illustrates how serious drinking problems have become among juveniles in thee county. As of October this year police had arrested 205 juveniles on charges of being drunk in public and 94 on drunk driving charges. During the entire year of 1976 there were 158 juveniles arrested on drinking charges in the county and 79 on drunk driving charges.

Authorities at both Groveton High School and Mt. Vernon High where O'Donnell spent three days before his death, agreed that drinking has become a more serious problems among teenagers this year and is placing hard drugs as one of their more serious discipline problems. "It seems to be popular a mixture of beer and pot, as a replacement for hard drugs," said Mount Vernon Principal Thomas Higher.

Nationally a Gallup poll released yesterday said that a key reason behind growing alcohol abuse among teenagers is the fact that as many as one-fourth of the nation's parents do not have any rules or guidlines regarding the use of alcohol by their teen-aged children.

The poll said the incidence of drinking among teen-agers reflects a trend among adults towards increased consumption of alcohol.

O'Donnell's friends said he came from a strict home and often chaffed at some rules laid down by his military father. Once he ran away from home but only was absent from home one night and spent that time in a neighbor's apartment, friends said.

Coast Guard Petty Officer Jerry Bottcher, sponsor of the Mount Vernon Square Apartment's teen-age club, said he doubted O'Donnell realized what alcohol could do to him. "I'm quite sure he was not aware of a lot of the effects." he said "We drink once in a while and he just couldn't take it," a girl on the Groveton High School pep club said.

"He was real different." said Pam Main, 15, a sophomore at the high school where O'Donnell had defied tradition to join the all-girl cheering squad. But that, said Sheila Shrewsberry, 15, captain of the pep club, was another of O'Donnell's efforts to "be in with the crowd. But everyone rejected him."

A teacher at Groveton described O'Donnell as a student who needed prodding; others remembered him as a willing worker in many teen-aged activities. "He was a very good dude who would bend over backwards to help people," said Jeanise Gallahan, a 16-year-old Groveton High junior. But Lauton Ennis Jr. recalled a conversation in which O'Donnell vowed to run away from his Fairfax home and return to his native Washington state in search of his natural parents and family of seven brothers and sisters. Despite the efforts of hid adoptive family "he always felt he didn't belong" Gallahan said.

Police declined to release the identity of the other youngsters involved in the incident and said any decision on whether they will have to face criminal charges will be up to Fairfax Commonwealth's Attorney Robert F. Horan. Grimes said the detectives probably will meet with Horan today after they receive the toxicologist's report. An autopsy the toxicologist's report. An autopsy performed yesterday showed no signs of physical injury.

Grimes said police had no way of knowing whether O'Donnell could have been saved after he became unconscious. "You can only guess," he daid. "There's no way of saying for certain." Grimes said he knew of no other similar deaths in the country's history.