BUENOS AIRES, Argentina (JTA) – Posters appeared in a Jewish neighborhood of Buenos Aires reading “A good Jew is a dead Jew. The good Jew is Nisman.”

The posters in Villa Crespo refer to Alberto Nisman, the Argentine prosecutor heading the probe into the 1994 bombing of the AMIA Jewish center who was found shot dead in his Buenos Aires apartment on Jan. 18. His death remains unexplained.

No group or individual has taken credit for the unsigned posters.

DAIA, the Argentine Jewish political umbrella, expressed “concern” about the posters. DAIA President Julio Schlosser told the Argentine media that he will discuss the issue with national authorities.

Nisman, 51, was found hours before he was to present evidence to Argentine lawmakers that President Cristina Fernandez de Kirchner and other government officials covered up Iran’s role in the AMIA attack.