An elderly North Korean defector is being investigated by South Korean police for allegedly leaking information about other escapees to Pyongyang’s brutal secret police, a rare case of authorities accusing a defector of working with the DPRK regime to accomplish its goals.

The Ulsan Metropolitan Police told NK News on Monday that it is looking into the unnamed woman in her 70s on charges of violating the National Security Act by handing over other defectors’ personal information to Pyongyang’s Ministry of State Security, the DPRK’s secret police dealing primarily with political and ideological offenses.