I don't know if there's many major outlets that are primarily investigative in the era of the 24/7 news cycle and the accompanying need to always have something fresh on the front page, but at least in the English-speaking world the various newspapers of record (think places like the New York Times or the The Guardian) still have a decent newsroom and publish original investigative pieces. In audio formats, NPR and the various constellations of associated organizations like the Center for Investigative Reporting do excellent work as well. There's also organizations like Bellingcat that specialize in deep-dive investigations using open-source intelligence, presented in a "just-the-facts" format without editorialization.