The 32-year-old man arrested last week for taking five hostages at knifepoint at a bank in Aichi Prefecture has said he copied similar cases in the past, investigative sources said Monday.
"I imitated past standoff cases I saw on TV," Koji Nagakubo was quoted as saying at the time of his arrest Friday, after police stormed the Toyokawa Shinkin Bank's Zoshi branch to rescue the hostages about 13 hours after the standoff began.
The police are investigating what he may have learned from past cases, including one in 1979 in which a man took more than 30 hostages and killed four at a bank in Osaka.
Shortly after his arrest, Nagakubo said he took the hostages to demand the resignation of Prime Minister Yoshihiko Noda, according to the sources.
Police also suspect Nagakubo threatened a waitress at a restaurant with a knife three days earlier and dined and dashed.