A 16-year-old Washington youth was convicted Tuesday of murdering a Washington man who was fatally shot during a holdup attempt. It marked the second time in four years that Joseph(Joe Joe) Nicks Jr. has been convicted of participating in a street robbery that caused a murder.

In 1976, Nicks was found guilty of murdering Washington socialite Gladys Werlich, 85, who was killed when Nicks and three other youths attacked her during an early-morning walk. Nicks, who was 12 at the time of the Werlich killing, was released from prison after serving less than two years.

About two years after his release from prison in 1979, Nicks and another young man, John D. Hart, 19, were charged with killing Orlando Gonzales-Angel, 27, during a holdup near 17th and T. streets NW at 1 a.m. on Nov. 27, 1979.

At the urging of Nicks, Hart shot Gonzales-Angel in the back with a gun that Nicks and others had stolen four days earlier from the headquarters of the National Rifle Association, the government said.

A D.C. Superior Court jury deliberated for about an hour Tuesday before finding Nicks and Hart quilty of murder and several other robbery-related charges.

Nicks could be sentenced to life in prison if Superior Court Judge Carlisle E. Pratt decides to sentence him as an adult. Pratt also has the option of treating Nick under special federal rules devised for youths that would make Nicks eligible for parole immediately after he had entered prison.

Assistant U.S. Attorney Reggie B. Walton, noting that Nicks twice had been convicted of committing murder, said the government would urge the judge to sentence Nicks under stricter adult provisions of the law. Sentencing for both Nicks and Hart is scheduled Dec. 8.

Nicks, who was raised by his grandmother, was living with a friend without adult supervision at the time of the Gonzales-Angel killing, prosecutors said. At a bond hearing earlier this year, prosecutors stated that his mother was a drug addict, his father could not be located and that his grandmother no longer was able to supervise him.

After his arrest, Nicks made a statement to police, but Judge Pratt ruled that the statement was not admissible at trial because the youth has a low IQ and is not able to make independent judgments, according to prosecutor Walton.

Although he completed the seventh grade, Nicks has only kindergarten-level reading ability and is dominated by olderyouths, according to court papers filed by his lawyer.

Nicks and two others also were charged with breaking into the NRA's Scott Circle headquarters on Nov. 23, 1979, and stealing the .22-caliber semi-automatic murder weapon, as well as seven other guns and a supply of ammunition.

Nicks was convicted of the Werlich killiing after he gave police a detailed description of how he and three other youths accosted the victim after they had spent much of the morning of Jan. 13, 1976, seeking robbery victims. Nicks said that one of his friends tried to snatch Werlich's purse and a second youth knocked her to the ground. Nicks said that he and the fourth youth did not touch the victim.