Who's the mystery guest?

Ah, Google alerts. What random stuff they do turn up. Fun story today from Lawrence County, Alabama, about a mystery at the Lawrence County Commission Building. Basically, they want to install a surveillance system to figure out who keeps entering the building after hours and, well, not stealing anything or doing any damage, but:
King said someone has loosened door knobs and left trash in the hallway and items on her desk.
Why is this a problem?
The time the office staff spends making sure no one has taken anything from the building cuts into work time, she said.
Why do I find this hilarious? Probably just because I'm a bad person. But, pretty clearly, it's either an employee who's just completely screwing with County Administrator Peggy King or these folks just aren't all that good at closing their windows or something.
Office staff members haven’t found anything to be missing and there is no sign of forced entry. King discussed the issue during her report at the end of the commission meeting. She said she was hesitant to bring up the problem but said it was necessary because the incidents are reoccurring. “I have no idea why or how anybody gets in,” she said after the meeting. “The ‘why,’ simply because it’s random, and the ‘how,’ there’s no forced entry, so you just have to speculate on that.”
So, it's either someone who has a key (can't be that many people, and they've changed the locks four times in the past two years), or they're getting in some other way that doesn't involve doors with locks. It's got to be someone who works there and just doesn't like the boss, right? But what kind of operation is being run in that place anyway?
During the meeting, Commissioner Bradley Cross asked how an unauthorized person would enter the building if doors were locked, and Commissioner Mose Jones replied that people entering the building after operating hours has been an ongoing issue. Such activity in the commission building resulted in the installation of a glass door separating the lobby and some staff offices during former Administrator Peggy Dawson’s time in office.
The commission building is staffed by a bunch of late-night party animals who don't have anywhere better to go than back to work? Isn't there a decent bar in town or something? So, King gets everyone together in a meeting and asks, "Alright, who's coming in after hours and putting trash in the hallways and stuff?" Everyone just sits on their hands. "No, seriously, who's coming in at night and putting the little troll dolls on my desk? It's not funny, alright." Snickering. "No one's going to admit to being in here last night? I know someone was in here. There were Miller High Life cans all through the hallway when I got in, people. I know I wasn't in here enjoying the champagne of beers at all hours! This has absolutely got to stop!" Peter, from HR, pipes up: "I'm a Bud man, myself, Ma'am." Steam issues from King's ears.... So King is going to solve this problem:
King told The Daily she wants to install the surveillance system because changing the locks again might not be effective and won’t reveal who is entering the building after hours.
Anyone want to put in a bid?