Public prosecutors said on Friday that Peter Hartz, the former human resources chief of German car giant Volkswagen, was under investigation on suspicion of possible breach of trust in the bribery and corruption scandal at Europe's biggest car maker. Hartz's offices at VW had been searched and potential evidence seized, the prosecutors said. Hartz, who has strenuously denied any wrongdoing, resigned in July as the scandal at the car maker snowballed. Press reports have alleged that Hartz, a close ally of Chancellor Gerhard Schröder, had effectively issued a "blank check" to VW's works council in order to "buy" labor representatives' approval of tough corporate restructuring measures. The reports claimed that Hartz had given clear instructions to make cash available for the business trips for members of the works council, but required no justification for the expenses. Some reports alleged that the money had been used to pay for council members' pleasure trips to Brazil, stays in luxury hotels and even for visits to prostitutes. One of Hartz's co-workers, Klaus-Joachim Gebauer, who was in charge of organizing the trips, is already being investigated by prosecutors for allegations of fraud and abuse of trust.