Police took complete video recordings during 87.6 percent of fiscal 2018 interrogations in criminal cases bound for lay judge trials, National Police Agency data showed Thursday.

As the recording of interrogation video and audio will become mandatory in June based on the revised criminal procedure code, police have ratcheted up transparency efforts on a trial basis. The making of full recordings is up from 81.9 percent of interrogations in fiscal 2017.

Lay judge trials, which involve regular citizens making judgments on serious criminal cases, represent some 3 percent of all trials in Japan. Critics point to a lack of transparency in interrogations conducted by police, as lawyers are not allowed to be present during questioning.

Among the 3,266 criminal cases in fiscal 2018 subject to lay judge trials, no recordings were made in 136 cases. A total of 131 of them were crime syndicate cases, which are exempted in order to protect witnesses and associates of the accused.

Interrogations were partially recorded in 270 cases, of which 75 resulted from investigator error, such as forgetting to start the recording of an interview. In many other cases suspects refused to be recorded.

The average total length of video recordings per case was 25 hours and 42 minutes, up 61 minutes from the previous year, according to the agency.

As for interrogations of suspects with intellectual disabilities in both lay judge and professional judge cases, complete recordings were made in 99.9 percent of instances, according to the agency.