Hi Vera, thanks for your concern, here’s what I have been able to find out:
Initially I assumed the owls were trapped, but according to observers they had a way in and out. There was a large infestation of rats in the building they were feeding on, so it looks like they succumbed to rodent poison. The good news is the DNR was called and investigated the situation, this is what I’ve been told. If anyone reading this has a hotline to the DNR people, maybe they can elaborate, I think the situation should be discussed and remedied. Im trying to get pics from park district employees that were there. Unfortunately there doesn’t seem to be much interest in this topic.