Stuart L. Kreiner, the 16-year-old charged with the stabbing deaths of three young girls in his northern Anne Arundel County neighborhood, will stand trial as an adult, a county Circuit Court Judge ruled yesterday.

Kreiner's lawyer had sought to have the murder case transferred to Juvenile Court for trial. Then, even if Kreiner were found responsible for the murders, he would have gone freeat the age of 21, when the juvenile court's jurisdiction ceased. he also could have received psychiatric treatment under court supervision.

Judge E. Mackall Childs, however, ruled that Kreiner's age, the nature of the charges against him and the question of public safety all require that he be tried as an adult.

Kreiner, a slight, bespectacled youth apparently shunned by many of his contemporaries, was charged last October with the stabbing deaths of sisters Deborah Hogan, 10, and Theresa Hogan, 8, and their playmate, Ann Brzeszkiewicz, 8,. The girls, who lived less than a block from Kreiner's home at 7973 Cross Creek Dr., in Glen Burnie, were found dead in a shallow, muddy stream a few hundred yards from their homes.

In a hearing April 17 before Childs, two psychiatrists who examined Kreiner at the Clifton T. perkins State Hospital, testified that the boy's case should be transferred to juvenile court.

Dr. Jones R. Rappeport said that while Kreiner would be 17 in August, "psychologically he functions at a much younger age," at the level of a 12-year-old.

Rappeport described Kreiner as a youth sufferings from a mental disorder that left him "the outsider, the odd man out" among his peers. He said such individuals, often quiet and withdrawn, are unable to express their feelings and build up tremendous frustrations.

"There is a final insult , a final thing . . . and such individuals may explode," Rappeport said under cross-examination by Deputy State's Attorney David Cuttler.