I would talk to my local police department and see if they can help start up a neighborhood watch program. Then get it going...
I would keep my cell phone with me at all times so I could take a picture of the creep. Did the police come out? Did they take pictures - maybe dude left shoe prints??? If he's wearing gloves in the summer? Sorry - I would suspect immediately...just like I am when I see guys wearing the LONG duster jackets in the summer...whatcha hiding under there, dude?
While I totally support posting the sign? it would be a warning to him as well...do you want him caught or gone? If you want him caught (and hopefully GONE!!) i would alert neighbors to be watchful.
I am TOTALLY for posting a sign. Don't get me wrong....
Many people get "comfortable" in their surroundings. So they stop looking beyond their nose. Remind people to LOCK doors. LOCK windows...
Ask the management company to beef up security so the guy can be caught...while it is costly...ask if they are going to install cameras or better lighting so this guy can't lurk in the shadows?
If you live on the first floor - make sure your windows and doors are LOCKED. Put safety bars in as well. If you can - install an alarm system as well.
another thing to remember...
Lock your car when you are pumping gas...people are distracted and don't pay attention...
Look in your back seat - open back doors when getting in your car...you never know what people are willing to do these days!!
Maybe I watch too many crime shows!! Be careful. Pay attention to your surroundings...