I am a police officer in Florida. One night, while working the midnight shift, I was dispatched along with another police officer to the scene of a delayed burglary call. The burglary had occurred at a vacant residence, which was located in a rural area and located directly next to an old, closed down and vacant feed store. The feed store had been broken into as well, so myself and the other officer had a lot of work ahead of us.
I entered into the vacant feed store through the front door, and immediately heard what sounded like a "PSSST" type sound. It immediately made me perk up, because it legitimately sounded like someone was saying "PSSSST", as if to get my attention. I looked around with my flashlight and did not find anything there. Thinking my mind was playing tricks on me, I continued about my work and began processing the crime scene for evidence. It should be noted that I was completely in work mode, and not thinking about anything ghost related or paranormal related whatsoever.
After a short time, I exited the feed store to retrieve more supplies from my patrol car. When I walked back into the feed store, this time I immediately heard a loud, quick whistle. It was loud and distinctive enough to make me snap my head around, again sounding as if someone was trying to get my attention. This time, I yelled out "Hello!" and looked around again with my flashlight. Nothing there. For a second, I truly thought maybe the suspect in the break in was still inside and trying to play games or something. But I dispelled that notion after I searched the whole inside of the store and found nothing.
By this point in time, I was slightly freaked but knew that I still had a crime scene to process and a report to write. I shrugged the noises off and concentrated at the task at hand. After a while, I had finished in the feed store and responded back to the original residence, where the other officer was processing his crime scene. I did not mention what I had heard next door, as the other officer probably would have laughed and called me a scaredy cat.
While I was helping him process his scene, he told me the owner of the vacant residence had gone home, as the processing was going to take a long time, and it was about 2:00am. After about 15 minutes or so, we both distinctly heard the sound of a car door opening and closing. Thinking it was the owner, I mentioned to the other officer that the owner must have returned to the scene to check on our progress. Only thing is, no one came into the residence. About 5-10 minutes later, we both heard a car door open and close a second time. This time I said, "I wonder what that guy is doing out there?" Again, we both shrugged it off.
Now, picture this: My patrol car is parked directly in front of the residence, with the front door wide open and my headlights on to provide us light in the house (the house was vacant and therefore had no power). About 5 minutes later, we heard a car door open and close for a THIRD time. This time, the sound of the door closing was significantly close, and sounded exactly like my patrol car door. Thinking that some crazy person had maybe entered my patrol car to try and steal it, we run outside IMMEDIATELY after hearing the sound. We were outside by my patrol car in about 3 seconds. Now, I do not know any human being who could escape detection in 3 seconds. But I swear to you, the owner was NOT outside, and in fact we did not see ONE HUMAN SOUL outside at all. No sound of anyone running away, no one hiding underneath or inside our patrol cars, no NOTHING.
The other officer was more freaked out than I was. We agreed never to talk about it. To this day, this event remains unexplained.