A judge dismissed charges of assault with a deadly weapon yesterday filed against a District man infected with AIDS who is accused of sexually abusing six children.

It was believed to be the first time someone had been charged with using the AIDS virus as a weapon.

Superior Court Judge Ricardo M. Urbina made a decision after the prosecution finished presenting its case against Michael A. Feaster, who was indicted in 1989.

Feaster still faces 32 counts that include sodomy, taking indecent liberties with a child and cruelty to children.

Prosecutors defined the weapon as the "defendant's penis, his semen and other bodily fluids, and the virus."

None of the children has tested positive for the AIDS virus.

Although AIDS antibodies can usually be detected within six months of infection, a negative test result does not ensure that someone will not test positive in the future.

Urbino's ruling came on a motion for acquittal made by Feaster's attorneys, K. Duff Lewis and Richard Ripley.

In its presentation, the prosecution was unable to prove the essential element in the charge: that the virus was transferred to one of the victims.

"There was no evidence of a bodily fluid that was transmitted or exchanged during the alleged act," said Ripley.

All three charges of assault with a deadly weapon involved a victim who was 13 years old when the alleged assaults took place two years ago.

Ripley and Lewis declined to discuss the significance of Urbino's ruling because the case is still being tried.

A spokeswoman for U.S. Attorney Jay B. Stephens also declined to comment on the case for the same reason.

The 41 charges in the original indictment have been reduced to 32.

Among the others dismissed or withdrawn during the trial were those involving a victim who is now 18 years old.

Urbino struck his testimony from the record this week when the victim said he was unsure of the difference between telling the truth and telling a lie.

Feaster is charged with taking indecent liberties with six boys, although he is charged with having forced sex with the only one 13-year-old.

The incidents allegedly took place in a house at 10th and K streets NE, where Feaster lived.

The boys, who ranged in age from 9 to 15, came into contact with Feaster when he took care of neighborhood children.