AN investigation was under way yesterday after an 18-year-old inmate, surnamed Cheung, jumped to his death from Cape Collinson Correctional Institution. Cheung - a convicted robber - was said to have jumped suddenly from the corridor outside a classroom on the second floor as he attended an education television session with seven other inmates yesterday morning, a government official said. He was certified dead shortly after being admitted to Eastern Hospital. The reasons behind the fatal leap were not known. 'It will be at the heart of investigation by the board of inquiry,' the government official said. The police have been informed of the death. Cheung was convicted of robbery on February 14 and was admitted to the institution on February 24 this year. A post mortem examination will be held later this week.