I know for a fact that a few Oklahoma Guard Blackhawk copters doing Night Vision Goggle Training landed at an unlit airstrip one night (it's easier with goggles if there are no runway lights on) and some locals, (PD or Sheriff) had them remain there to confirm they weren't smuggling drugs.

Another time I had a little go round when I landed a Piper arrow at night at my home airport in Texas. Airport runways were unlit, but good lighting surrounding the airport made it easy to find and land at night. There were two City Pd, two county, and even an off duty State trooper showed up. When I asked what the problem was one city pd guy said you landed after dark, and there are no runway lights. I said "So what is the problem"? He repeated himself, and so did I. This went on for SEVERAL repetitions. His compadres remained silent. I thought he might catch on to what I was doing (messing with him a little), but he didn't so I became bored, and finally said there are no FAA regs prohibiting it, and I didn't believe there were any local laws either unless he new of them specifically. He then asked to look in the plane. I said it's not my plane, and he'd have to ask the owner who had been with me. The owner said it was okay, and the local didn't know how to open the door, so he just looked in the window, and then he said it looked clear.

They felt there were drugs being flown into that airport and another one in the county. I don't think they even new about the 4 Pvt strips.