A former police officer pleaded guilty on Monday to second-degree manslaughter in the shooting of an 18-year-old deli clerk last year in Queens, telling the judge it was tragic case of horseplay. An indictment had accused John Malik, 60, of recklessly firing a semiautomatic pistol at the victim while cashing a lottery ticket inside the deli the night of Oct. 18, 2004. Mr. Malik originally told the police that he had been waiting for his lottery tickets around 11 p.m. on Oct. 18 when his pager went off. He claimed that when he reached for it, he jostled his .380-caliber SIG Sauer semiautomatic pistol in his holster. A single shot struck the clerk, Manuel Chametla, 18, who was about 8 or 10 feet away, behind the counter of the Astoria Food Mart at 31st Street and 21st Avenue. But Mr. Malik changed his story yesterday, before Justice Randall T. Eng of State Supreme Court in Queens, saying the shooting had resulted from "horseplay." He had been on the way to work at a security company, he said, his gun holstered in a belt clip inside his waistband, until he drew his gun in jest in response to something Mr. Chametla had said. The bullet struck and killed Manuel Chametla, an 18-year-old Mexican immigrant. During the sentencing, he turned and apologized to the victim's family. Malik, who served on the police force 28 years, faces a term of one to three years in prison at sentencing on June 14. [more] and [more] and [more]