The National Police Agency's 2008 police white paper shows that investigators are finding it increasingly difficult to obtain information from witnesses, suspects and others during criminal investigations. Behind this is increasing public indifference to others, growing distrust of the police, and a reluctance on the part of those interviewed to disclose personal information about themselves and others — an adverse effect of the Personal Information Protection Law. As a result, the ability of society to prevent crime is declining.

According to the white paper, investigators were able to make 10,464 arrests of criminal suspects in 1993 based on information gained through interviews. But the corresponding figure dropped to 7,494 in 1998, 5,558 in 2003 and 4,820 in 2007.

In a multiple-answer poll of 2,454 police detectives conducted in January 2008 and cited by the white paper, 79.2 percent found it difficult to gain people's cooperation. The examples of noncooperation cited include: refusal to submit related materials on a voluntary basis (52.3 percent), refusal to disclose the names of other people during questioning at police stations (43.2 percent) and refusal to offer information when visited and talked to by detectives (29.8 percent).

To improve the police's investigative capabilities, the white paper calls for strengthening the DNA database, building a database for drawing three-dimensional images of suspects and utilizing wiretapping and profiling. But for criminal investigations to be successful, they still require traditional detective work.

According to the white paper, false charges leveled in a 2002 rape and attempted rape in Himi, Toyama Prefecture, and in a case of vote-buying in the 2003 Kagoshima Prefectural Assembly election apparently lowered public trust in the police and made them less willing to cooperate with detectives.

The NPA must strive to eliminate investigative irregularities and have police officers embrace measures such as videotaping of interrogations. Doing so will bolster public trust in the police and, in turn, enhance the effectiveness of detectives' investigations.