CSI Mentality

I read somewhere that local police departments and detectives get frustrated because people see these high-tech labs on TV shows like CSI that can get things like DNA results pretty much instantly, when in reality, most departments have to send them off to a regional lab where there is a back-up of specimens. (Or something like that.)
But sometimes it would be nice if they even pretended they were capable of investigating clues.
When I went out to get the mail today, I noticed an exploded Gatorade bottle sitting in our yard. I just figured someone had thrown it in the road, and then another vehicle had hit it.
Then I got out to our mailbox, and I noticed bits of aluminum foil inside it with liquid residue all over the inside and around the seams on the outside. I don't know how many of you are familiar with teenage pranks, but I recognized it instantly as leftovers from a pop-bottle bomb that uses a reaction of aluminum foil and Draino to cause a pop bottle to explode. (I never vandalized anything with this, but it was popular with friends at Independence Day celebrations.)
Our mailbox wasn't damaged, other than the fact that the door won't latch shut, which just requires pliers to fix (I'm pretty sure, at least), and gross liquid all over. Had it just been this, I would have said, "Stupid punk teenagers," and went on with my day. But we had a Netflix DVD in there when they put this contraption in there. I had noticed the door hanging open yesterday (no mail due to the holiday), but didn't see the red envelope inside. (I didn't actually go check, as it is hard to escape the house without Munchkins following, and I didn't know what had happened until I went out to get today's mail.) I figured that the punks either stole the DVD (federal offense), or at the very least damaged it (which I'm pretty sure is an offense as well), so I called the Sherriff.
The Sherriff's officer came out, asked me a few questions, and then left, without so much as looking at the mailbox any more than a drive-by in his vehicle. He did call me later and said he intercepted our mail lady, and she said that our DVD was inside the mailbox and she got it. (How she remembered our mailbox out of 300 or so on her route, I don't know; we'll see if Netflix recieves it.)
What bugs me, I guess, is that the officer didn't even look for clues. He didn't go out to the mailbox or even look at the bottle laying in the yard. I know that teenage punks probably wouldn't be "on the books," but why not take the bottle in and finger print it anyways? Maybe they would happen to catch the kids on something else - other vandalism or underage drinking. And say they have prints from 20 mailbox bombs that they can pin to the kid. Maybe a bit of community service would put him on the straight and narrow?
I don't know; it just kind of bugged me.