Ignition won't kill the engine(?)

Happened twice now, when I turn the key off, the engine does not quit, all of the inside eletrical goes off(radio, a/c) tried working the key back and forth several times, nothing. finally had to pull the line out of the fuse panel to kill it. Have not torn into the steering column, hoping it might be a little easier than that. :dunno:

My J10 did that all the time after I got the alternator working. But that was because the alternator was hot wired so with the ignition off the coil was still getting power. On the XJ I would assume this isn't the case. What fuse did you pull to get the engine to stop?