A Montgomery County grand jury cleared a county police detective yesterday of criminal wrongdoing in the Dec. 4 shooting death of a 17-year-old Wheaton youth who police said threatened the detective with a baseball bat as the officer sought to disperse a crowd of fighting young people.

The grand jury found no reason to indict Detective Michael J. Jones, who was attempting to stop several fights involving numerous young people at an Aspen Hill gas station. During the fracas, one youth, carrying a bat, "came toward the officer as if to strike him," according to police Sgt. Gary F. Smith, who oversaw an investigation of the shooting.

Jones, a 19-year member of the force assigned to the juvenile division, shot and killed the youth, David A. Bane, after Bane failed to heed the officer's warning to drop the bat, Smith said.

The grand jury's decision yesterday angered several of the dead youth's friends who said they saw the shooting and disputed the police department's account of what happened. Three of them said Jones failed to immediately identify himself as a police officer, and fired at Bane without allowing the youth enough time to put down the bat.

The grand jury reviewed evidence gathered by officers who questioned more than 30 witnesses who "gave a myriad of accounts," Smith said. "You name the possibility, and we heard it."

However, Smith said, most of the witnesses recalled that Bane moved toward Jones with a bat, and that Jones, who was off duty, fired one shot after identifying himself and displaying his badge. Many of the witnesses who agreed on that version "were adults, older people who were there but weren't involved in any of the fighting," Smith said.

Jones, who returned to full duty yesterday after working in an administrative job since the shooting, declined to comment.

In an interview last month, Vance Rego, 17, a friend of the dead youth, said that on Dec. 4, Bane and several other young people left a party about 11 p.m. and drove to the area of Connecticut Avenue and Aspen Hill Road in Rockville. A van that Bane had lent to a friend had broken down, Rego said, and the group pushed it to a Mobil station at the intersection, near a shopping center that is a popular congregating spot for young people.

An argument began between Bane and several young people who were not part of his group, according to Smith and Bane's friends. Within minutes, they said, about 15 people were fighting. They said Bane got his hands on one of several baseball bats that someone had taken out of a car.

In all, they said, about 60 people were gathered at the scene when Detective Jones, who was driving by in his own car, stopped to intervene.