Ignition switch lock

Due to the back hatch not being closed properly on my wife's 1997 Jimmy SLS the battery went totally flat overnight (no surprise there).
When my wife got into the vehicle this morning she didn't notice that the interior lights failed to come on, so she put the key in the ignition and turned it to start and of course - nothing.

Okay, then she turned the key back to withdraw it from the lock, but it wouldn't release. The transmission was in park still but there was no way the key would come out of the ignition switch. Any ideas - is there some kind of interlock between the transmission and the ignition switch? It's a real puzzler to me.

Thanks,
giner

You need electrical power to energize the interlock soleniod to remove the key.
There is also a way to remove the key if you lose power. Look on the left underside of the steering column below the ignition lock cylinder. There should be a plug there. remove the plug and with a long thin screwdriver, depress the brass button while you turn the switch to the off position.

Thanks, GM Merlin!