The National Police Agency may offer cash rewards to people who provide information on a series of cases involving personal computers infected with a virus that remotely posts threatening messages online.
The NPA believes people with pertinent information on the case may be outside the reach of regular investigative methods.
The reward system until now has been limited to cases such as murder, robbery and arson. The agency plans to revise regulations, possibly next month, to make the rewards applicable to cases involving virus-infected PCs, NPA sources said Monday, without specifying how big the rewards will be.
In the series of incidents involving the remote-control virus, the Metropolitan Police Department as well as the prefectural police in Osaka, Kanagawa and Mie mistakenly arrested four people, accusing them of posting threats online. The four later received apologies.
The four police forces have set up a joint task force and are reviewing their previous investigations while probing the virus, which they are treating as causing forceful obstruction of business.
The reward system was launched in 2007. Payments have been made to informants in the murder of a British woman in Chiba Prefecture and suspects in cases involving Aum Shinrikyo, the cult behind the 1995 sarin gas attack on the Tokyo subway system.
As of Monday, police were accepting information on 17 current cases in exchange for rewards.