Trigger owner vs session owner

[RW Shore]

1. When a trigger fires, does it run with the grants of the current session owner or with those of the trigger owner (the user that executed the create-trigger statement)? It seems to me that I read some documentation about this, but I'll be darned if I can find it now (suggesting that an addition to section 19 of the documentation may be in order). I'd like to be able to have a trigger update tables that the user can't simply do an update against; that is, I'd like the trigger to run with the grants associated with the trigger owner rather than (in addition to?) those of the session owner.

2. I know that when executed inside a trigger, the USER() and CURRENT_USER() functions refer to the session owner, not the trigger owner - I tested this much. Is there a function that tells me the trigger owner rather than the session owner?