Hi Jaber,
Actually, jBPM 4.3 didn't record the starter of process instances. Maybe you could join our discussion for this feature. There is the post url:
http://community.jboss.org/thread/150854?tstart=0
And the setAuthenticatedUserId() method used ThreadLocal to store the userId. It could transfer the login userId from outside of process engine to inside. So the component in process engine could use this userId to do something.