MOBILE, Ala. (AP) — The head of a company that constructs ships for the U.S. Navy on the Gulf Coast has resigned following an investigation by federal and Australian authorities. A company statement says the chief executive of the Mobile-based Austal USA, Craig Perciavalle, has stepped down and will be replaced by an interim leader. The statement says the Justice Department, Securities and Exchange Commission and Australian securities regulators have been investigating financial and procurement practices dating back to before July 2016. Perciavalle’s resignation was announced about two years after a law enforcement raid at the offices of Austal USA. No charges were announced.