West Palm Beach - A 14-year-old boy charged as an adult with murdering his teacher in May 2000 returned to the witness stand yesterday for cross-examination by prosecutors attempting to show the schoolhouse shooting was intentional. Nathaniel Brazill, who was 13 at the time of the shooting, is on trial on a first-degree murder charge in the killing of Lake Worth Middle School teacher Mr Barry Grunow (35), and faces life in prison if convicted. He testified that the gun went off accidentally as he pointed it at Mr Grunow, whom he described as "a nice guy, a good teacher".