Sorry about the delay in updating this issue, but I've be waiting to see how this plays out.
This is going to be a long one.
First, I reported the issue to building management and they replied that they have been finding those mini-liquor bottles all over the upper level (where I park) of the parking garage. They suspected it was teenagers drinking underage or, like I had, the construction workers.
However the construction has since finished, the workers have left, and the liquor bottles keep turning up. So that's one suspect(s) eliminated.
Then things got interesting starting Wed. Dec 4th.
During the week I normally leave for work around 7:30am and return home around 5pm. So my car sits in the parking garage overnight and if a mini-liquor bottle turns up I won't find it until 7:30am in the morning. But that Wednesday evening I went down to the garage a little before 8pm to get something out of my car and and
surprise mini-liquor bottle on my car's antenna.
So it now it looks like the culprit strikes, not during the wee hours of the morning, but surprisingly enough during a three hour window after I get home from work. This is odd, as there is a lot of vehicle and foot traffic through the garage at that time as people come home from work.
The next day, Thursday, I was working from home so I was able to report this new information to the building manager who agreed that it was an odd development.
I now had an idea.
Who's up for a stake out?
That evening around 5pm I went down to the parking garage and checked on my car. No bottles, nothing under the door handles. I then wandered down to the far end of the garage where the vehicle entrance is and took up position next to one of the support pillars. From this position I could keep an eye on both my car and the interior door leading to the elevators. This meant I could see anyone going near my car and going through the doorway.
To create the necessary Raison d'être
http://en.wikipedia.org/wiki/Raison_d%27%C3%AAtre I had my cellphone out and pretended to be texting.
For several minutes I watched as a number of vehicles entered the garage but none parked near my car nor did their occupants approach it on their way to the elevators.
Then a car entered the garage and pulled into the parking space directly behind mine. My suspicions were aroused by this because there is usually an SUV, not a small compact like this car was, in that spot. As I am watching this car the driver (I can only tell it is a man from where I am standing) exits and starts walking around to the passenger side (which would put him on the antenna side of my car) he then opens the passenger side door and climbs into the front passenger seat. A few seconds later I notice he's shining a flashlight around the interior and then, apparently, up at the ceiling of the parking garage. Now I'm really suspicious. Is he looking for something in the car or up on the ceiling? If he's the culprit, he may suspect that a camera has been planted above my car.
While this is going on another car, that I do recognize, because it parks just around the corner from me and I pass it on the way in and out of the garage everyday, pulls into the garage and parks in its usual spot. This is a little over from my car and a little closer to the garage entrance (and to where I am standing).
Now I've got two cars to watch that are a bit apart from one another so I can't watch both at once. I keep most of my attention on the first car whose driver eventually turns off the flashlight, closes and locks his doors, and heads off to the elevators, passing by my car on the way, but leaving it untouched.
Okay, one down, one to go.
I now turn my attention to the second car, but now notice that its driver is nowhere in sight. The car's there but no driver. He could have gone to the elevators while I was watching the first car. But, if you recall, I was standing where I could not only keep an eye on my car but the door to the elevators as well and had not seen anyone except the driver of the first car go through them since the second car had entered the garage. So, where had this second driver gotten to? There is another door on that level to the elevators but its all the way around the other side so I doubt that he would use it.
Anyways, I'm mostly suspicious of the car which parked behind mine (as it turned out it was a red herring: I'll explain later) so I leave my position and start to walk towards it. To do so I will have to pass by where the second car is parked. Just as I'm coming up to it I find out where it's driver had gotten to.
There he is, a man in his late 50s or early 60s? (I'm guessing) Sitting casually in a canvas folding camp chair he has placed next to his car (that's why I couldn't see him, his car was hiding him from view). In a cup holder in the chair is an open can of beer while in one hand he has a lit cigarette and from the other he's drinking from a
mini-liquor bottle 
Okay, suspect sighted.
Problem is, suspect has sighted me.
Oh, well. He doesn't react to seeing me there, so I suppose he doesn't recognize me. I make a note of which parking space he's in and head back to my apartment.
The next day, Friday, I managed to get home early from work, before the management office closes, and reported what I had seen the evening before. They are now aware of this guy and that he is drinking in the parking garage which, if I understand our liquor laws, is drinking out of residence, and is illegal.
These bottles were showing up at least two or three times a week. Since my stake out, not a one. So I'm hoping that either I've scared the culprit off or they've found something else to do with their empties.
Now as for why the old guy would be smoking and drinking in the garage and not in his apartment. He may have a wife who he can't smoke around (and maybe can't drink around either). Our apartments do have balconies but its too cold this time of year to use them. Which brings up another fact. This bottle issue did just happen to start right around the start of the cooler weather.
Finally, about that first car and the deal with the flashlight. Turned out that the guy was either a new tenant or had a new car and was putting his parking sticker (the thing that shows you belong in that parking space) on the window and needed a flashlight to see what he was doing.
