Luis Gerez, 50, who has been missing since Wednesday, reappeared shortly after President Nestor Kirchner made a nationally televised appeal for his safe return, the BBC reported. Gerez had testified against a former police chief, accusing him of numerous abuses during the 1976-1983 regime known as the Dirty War.

According to the Spanish news agency EFE, Gerez said he was kidnapped and released, though never learned the identity of his captors.

He was the second witness to disappear in recent months.

Julio Lopez disappeared earlier this year after testifying against another former police chief.

Some 30,000 people were killed or disappeared during the dictatorship.