A 16-year-old boy who had been placed under a court order in a city-contracted juvenile shelter recently was released by officials there into the custody of a man who, according to police, later assaulted the youth sexually and held him captive after taking him to live in his Northwest home.

Supervisors at the Kennedy Street Shelter, where the youth had been sent to await trial on criminal charges in Superior Court, yesterday declined to comment why they turned him over to the man, who police said had posed as a court employe, on June 15.

Audrey Rowe, director of the D.C. Social Services Commission, which pays the shelter to take care of juveniles, said yesterday that she has ordered an investigation of the incident.

"It appears as though a person did represent himself to us as well as the court as someone who had authority to take custody of this child," Rowe said. "I want to know how it happened just as bad as the police do."

According to police affidavits filed in D.C. Superior Court outlining interviews with the 16-year-old youth, and the director of the shelter, D.C. Corporation Counsel attorneys have determined that the boy's release from the shelter was not authorized by the court.

The shelter's director, Larry Jiggetts, confirmed the incident but said "I was asked not to say anything to anyone."

The man involved, Charles VonByrd, 41, of 5403 Dix Street NE, described in court papers as a self-employed carpenter, was charged last year with taking indecent liberties with a minor in connection with an apparently unrelated incident last year involving a 13-year-old boy. VonByrd has not been charged in the recent incident involving the 16 year-old.

VonByrd's attorney, public defender Mary Lou Soller, declined to comment on either case.

Information concerning VonByrd's alleged assault on the 16-year-old, and how shelter supervisors released him, is contained in a lengthy police affadavit attached to a search warrant, which was issued in connection with VonByrd's arrest this week in the earlier case involving the 13-year-old youth.

In the affadavit, VonByrd is alleged to have taken indecent liberties with four other youths over a five-year period.

Rowe said that VonByrd, who was released into third-party custody after appearing in Superior Court on the charge earlier this week, was previously an employe of Questover, a group that until a year ago was under contract to the city to provide shelter for emotionally disturbed youths.