Hiroshima Prison officials announced Tuesday that a prisoner -- assumed to be Fumihiro Joyu, the second-in-command of Aum Shinrikyo -- was to be released at 6 a.m. this morning. Hiroshima Prefectural Police will deploy about 150 officers in the area around the prison and Hiroshima Airport to prevent trouble, police sources said. Joyu, 37, is expected to fly to Tokyo from Hiroshima this morning. Joyu, who has served three years for forgery and perjury, is expected to be greeted in front of the prison gate by Aum followers. He will probably be driven in an Aum car to the airport, in the nearby town of Hongo, they said. The former cult spokesman reportedly ranks second after Aum founder Shoko Asahara, 44, who is on trial on charges of ordering a series of crimes by cult followers. It is believed Joyu will become Aum leader after his release.