Lain has a key. Rattle at the quarantine main gate - guard will speak -then go to the east house where Lain lives and ask after his friend.

Money of the dead guy? That's a hint for the 4 treasure maps you have to find. More spoilers?
Kiya

http://www.kiya1.via.t-online.de/images/Div_Poor3.jpg.html

pic shows where Lain lives - your choice <img src="/ubbthreads/images/graemlins/wave.gif" alt="" />