A charge was dropped yesterday against a 13-year-old District boy who was arrested Monday night after police said he accidentally shot and critically wounded his 9-year-old brother as they played with a handgun.

The boy, who spent the night in a juvenile facility, was released after a prosecutor told D.C. Superior Court Judge Stephen F. Eilperin that no formal charges would be filed in the shooting, which occurred when the two boys played with what they apparently thought was an unloaded gun they found three days earlier in their mother's apartment on Good Hope Road SE.

The injured boy, Omar H. Palmer, remained in extremely critical and unstable condition at Children's Hospital last night, a hospital spokeswoman said.

The 13-year-old, looking stunned and nervous standing beside his lawyer, public defender Bruce Clarke, said outside the courtroom that at the time of the arrest police told him he "hadn't done anything wrong" and that "everyone makes mistakes." Police had said that when first questioned, the 13-year-old said that his younger brother had shot himself, then later changed his story to say that he had been holding the gun when it accidentally fired.

After the 13-year-old's release, lawyers with the Public Defender Service questioned why the boy was imprisoned at the D.C. Receiving Home for Children rather than placed in an emergency foster home after a police spokesman told the media Monday night that the "gun accidentally discharged." At that time, police had charged the boy with assault with a deadly weapon -- a charge that in the District requires proof that an act was "done knowingly or done voluntarily and purposefully and not because of mistake, inadvertence or accident," according to D.C. jury instructions.

"For a first offender who even the police say was involved in an accidental shooting to be incarcerated in that kind of setting the very night that his brother lies in a hospital seriously injured does not seem to me to serve the rehabilitative goals of the juvenile system," said Maureen Cannon, a lawyer with the Public Defender Service.

Police spokesman Lt. William White III, who called the shooting accidental Monday night, said yesterday, "It is not the function of the police department to make a final determination regarding the degree of individual responsibility. The court determines whether or not it was accidental or intentional."

As to the boy's placement in the Receiving Home, White said there were "extenuating circumstances" surrounding the shooting.

One police source said the extentuating circumstances included the discovery of stolen credit cards and a credit card processing machine in the apartment, a white powder believed to be cocaine, incorrect information on the lease, and an indication that the gun was stolen from out of state.