Prosecutors have decided that a 13-year-old boy charged with setting a fire that burned down three downtown Lewiston buildings and left 75 people homeless won’t be tried as an adult. District Attorney Norman Croteau said Thursday that he and the county’s juvenile prosecutor reviewed the fire investigator’s report and a psychological evaluation before reaching the decision. Allan Lobozzo, a lawyer for the boy, tells the Sun Journal, he was “delighted” to hear his client would remain in the juvenile court system. He says trying the boy as an adult would be “ludicrous.” The boy faces arson charges in connection with the April 29 fire. It was one of three large blazes in the city in a week. Another 13-year-old boy and two men face charges in the other fires.