How do you know if a timing chain breaks? Can this be caused by an oil leak?

I have a 2004 Chrysler Sebring, with a 2.7 V6 engine.  My engine was making loud rattling noises for quite some time.  My mechanic said it was due to a "lifter" and put some fluids in there to quiet down the car. Last year he changed out the water pump, but did not replace the timing chain.  When I was driving home the car just suddenly died.  I had another mechanic look under the hood, and he tells me the timing chain broke, and cracked the timing cover.