<< What year is the car? It's possible that the engine dying upon releasing
the key could be related to something else, especially if it's been working
fine since >>

It is indeed an older model -- a '94 Accord EX 2.2 sedan with 125+K miles.
It's never given me a moment's trouble in the 8 years I've owned it, which
might be why I'm jumping to conclusions. <g>
I'll start with a tune-up, which, based on the classic symptoms of flooding,
will most likely take care of the problem. I am, however, filing away
"ignition switch" for future reference. I do appreciate the heads-up.