After arriving at MIA terminal D from MAD, I went through global entry and dropped off checked bag. Then going on to connecting flights corridor I got to the section where you go left -making about 45 degree angle left to another corridor which leads to the terminals. (The terminal entrance being between DFS Cigars and Sweet Indulgences). As you made that left to get to the terminal and before reaching the actual terminal area, there was a uniformed person behind a podium. Is it TSA, border patrol, or airport security checkpoint? I ask because I was in a hurry to catch my connecting flight and the individual there asked me illegal questions and I wasn't able to catch their name and branch. Wore dark uniform and badge. Any help would be greatly appreciated so I can have a better idea of who to contact for my discrimination complaint. Thanks.