A federal grand jury here has indicted a 22-year-old counselor at the D.C. Children's assaulting and performing sodomy on three male juveniles at the school earlier this year.

The 13-count indictment, returned yesterday, alleges that Jasper Herman Hoskin of 610 Chesapeake St. SE, Washington, committed sodomy with three male students on July 5, July 8, Aug. 27 and Sept. 1. The sexual assaults allegedly took place in shcool buildings at the juvenile detention institution.

Two of the alleged sexual assaults were on a 13-year-old student, according to Daniel M. Clements, an assistant U.S. attorney. The other alleged assaults were on two youths aged 17 and 16.

Hoskin has been a counselor at the school for two years, Clement said.

Several of the charges against Hoskin fall under provisions of a recently revised Maryland rape statute. They charge Hoskin both with having sexual relations with someone under 15 years old while he is more than four years older than the victim and with third-degree sexual assault.

The other counts in the indictment charge him with unnatural and perverted sexual activities and assault with intent to commit sodomy.

If convicted, Hoskin could be sentenced to up to 60 years in jail.

Clements said an arrest warrant has been issued by the U.S. Park Police for Hoskin's arrest, but that he is expected to voluntarily surrender to law enforcement authorities on Thursday.