Sorry to hear about your misfortune. Hopefully both you and the car will be back to normal very shortly.
My neighbor across-the-street had the rear window knocked out of his minivan 3 nights ago, and over 10 years I've lost one side window and a tenant lost 1 side window in cars on the street. As you know, given your profession, kids do stupid things and a few low-lifes can cause a lot of damage, usually without any reason.

I'd suspect as Art mentions, that the window regulator was tweaked. You may even find it to be broken. The glass might have been working its way out of the metal track that holds its bottom edge. Any number of reasons contribute to stress in the glass. It's possible you tapped it just right with a ring or your watch as well- something had to have created a stress in the glass.

My guess is you may find an answer as you replace it- the regulator might be broken, or has been scraping the glass in the center, weakening it. All 740 door window regulators should be considered defective unless replaced- they are a real weak spot in an otherwise decent car.

And you may want to try the local drug store for cleaning supplies, there are some specifically designed to get out blood stains. Good luck.
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Rob Bareiss, New London CT ::: '87 244DL/M47- 230K, 88 744GLE- 220K, 82 245T-181K Also responsible for the care and feeding of: 88 745GLE, 231K, 87 244DL, 239K, 94 855GLT 189K