I killed few user sessions couple of weeks ago, Oracle show the session status as 'Killed' and never release those processes. I can't see session process id (spid) if I run the query against v$session and v$process. Whats going on here? could somebody explain ?

Bouncing database is not an option for me to clean held up processes and kinda resources are limited on these box so some how I need to clean these processes. How ?

Solaris 5.8
Oracle 8172