A Manassas youth charged with urging a man to slay a Reston teenager in September was acquitted of charges yesterday after a Prince William County jury deliberated 25 minutes.

Grorethas G. McKinnon, 17, who was tried as an adult on the charges, was found not guilty of the Sept. 30 slaying of Vidal Antonio Diamond, 17, who was shot twice in the head. "I feel great," said McKinnon, who is known as Sean. "It's been hell. I don't really feel that bitter. If I had been found guilty, I would be bitter."

McKinnon said his trouble was partly his fault because, "I should have been home. Now I will be careful where I go and who I'm with."

Prosecutors Paul B. Ebert and Rick Conway had argued during the two-day trial that McKinnon had urged another defendant, Terry Walker, 24, of Washington, to shoot Diamond to avenge an attempted fight at a fast-food restaurant. After the argument, Walker and several youths went to the Georgetown South neighborhood in Manassas where Walker allegedly got the gun used to kill Diamond, according to testimony.

Testimony from juveniles who were with the victim and with Walker and McKinnon differed substantially. Some witnesses testified that a youth identified as McKinnon had urged Walker to "Do it. Do it. Or give me the {gun} and I'll do it myself." Other witnesses said they could not identify McKinnon.

Defense attorney Mark Crossland said he believed the differences in the testimony led the jury to vote for acquittal.

"I can't believe it. I can't believe it," Mary Louise Diamond, mother of the victim, said after the verdict. "I lose a son, and he goes free. I can't believe it. Is it because the kids got on the witness stand and lied?"

Ebert, expressing disappointment in the jury's decision, said he is unsure if the verdict would affect other prosecution in the case.