The statute of limitations on the 1991 murder of a Japanese academic who translated Salman Rushdie's controversial novel "The Satanic Verses" is due to expire in 12 months, with the case as yet unsolved.

The Ibaraki Prefectural Police still maintains a special task force investigating the death of Tsukuba University assistant professor Hitoshi Igarashi, but it has uncovered no information that could help solve the case, investigative sources said.

Most of the officers who have worked on the case since the launch of the task force have been transferred to other sections, the sources said.