An Arlington youth's statement to police regarding the slaying of a District of Columbia taxi driver may be used in his trial, an Arlington Circuit Court judge ruled yesterday.

Judge Paul F. Sheridan ruled that the statement was admissible over the objections of the youth's attorney, who argued the youth did not fully understand his constitutional rights and that detectives delayed bringing him before a magistrate the day of the statement.

Ever E. Garcia, 17, is being tried as an adult in the death of Douglas R. Thornton, whose body was found in a Rosslyn parking lot in January. Jose G. Solis, 21, of 2321 N. 11th St., Arlington, also is charged with capital murder and robbery in the incident.

Thornton's body was found face down in an icy parking lot at 1720 N. Quinn St. Detectives testified yesterday that Thornton had been robbed of about $50 and that an autopsy showed he died of wounds to the head and hypothermia.

Two police officers said in court that when they first questioned Garcia about the incident March 21, he told them he had witnessed Solis "kicking" a man in the parking lot, and that he agreed to discuss the incident further the next day.

At noon on March 22, after several hours of intermittent questioning by police, "a statement ensued which implicated Ever Garcia in the murder and robbery of Douglas Ray Thornton," prosecutor Henry E. Hudson said.

Defense attorney Peter Baskin argued that officers should have taken Garcia before a magistrate earlier than 12:30 p.m., in accordance with a Virginia statute requiring "prompt presentment" to court officials of a juvenile in custody.

Hudson said that until Garcia's statement at noon, officers had no probable cause to arrest him and the youth was not technically in custody.