How about RSO living around this area? There are only 12 showing up on this map I found. I don't know where the apt is so I don't know if they are close to her place or not.
http://www.city-data.com/so/so-Palmyra-Pennsylvania.html
Is the "friend" a criminal? Does the neighbor have any other dealings with the cops? Is this the first time cops have been called for the noise?
I like the stepping out smoking cig, maybe the "friend" passed out (out til 2:00 am your pretty much drunk-) IMO. The creepy thing to me is the neighbor didn't answer the 2nd time-I don't know about others, but if I am mad enough to call the cops I won't be sleeping within 30 mins of them leaving.