An officer at the Osaka Detention House has tested positive for COVID-19, the Justice Ministry announced Sunday.
The officer, who is in his 40s, is the first in the nation from a detention house or a prison to be infected, the ministry said.
The ministry will identify those who had close contact with the officer, who lives in Hyogo Prefecture, and isolate them.
The facility in the city of Osaka houses trial defendants and convicts. The infected officer was in charge of four prisoners and supervised their work and daily lives. The prisoners, who have individual cells, had not shown any symptoms as of Sunday.
A colleague of the officer who was in close contact with him will stay home, and the facility will be disinfected.
The detention house said that another employee who has taken the coronavirus test is still waiting for the results, and that none of the facility's approximately 1,100 detainees is showing symptoms.
All of the 540 or so officers there have been wearing masks during their shifts.