The judge leading the investigation into Beirut's deadly 2020 port blast refused Wednesday to step down from the probe, rejecting charges brought against him by Lebanon's top prosecutor in the politically charged case.Investigative judge Tarek Bitar defied Lebanon's entrenched ruling elite this week by daring to charge several powerful figures -- including prosecutor general Ghassan Oueidat -- over the blast and reviving a probe that was suspended for over a year amid vehement political and legal pushback.