A federal grand jury is looking into charges that four NYPD detectives leaked top-secret information about the case of would-be Queens subway bomber Najibullah Zazi to his allies and to the press. Five more have been subpoenaed in the case, as have FBI agents — the leaks are being looked at as a side effect of simmering tension between local and federal law enforcement agencies. The Daily News reported this morning that the FBI is still mad that they were forced to arrest Zazi, who they’d been monitoring, earlier than planned due to the ham-fisted tactics of the NYPD. At the time, Barack Obama himself was reportedly briefed on the foul-up, and was not pleased. The NYPD isn’t talking about the grand jury probe.