I parked my Caprice in a garage, untouched, battery connected, for about one month. Upon attempting to start it, the engine would not turn over at all. The battery power seems to be fine: headlights are bright, instrument cluster is fine, the electrical systems seems to power up, (ie. the ingition and rear end sensors click) but the engine simply does not crank at all. I jumped with another car it just to make sure, but it had no effect. Any clues to what may be wrong.

Try to turn the motor by hand at the crank bolt. If it turns the motor is not locked up. Then the problem sounds like your starter :iceslolan

I replaced the starter a couple of days ago, which solved the problem. Thanks for the tip.