After spending close to two hours on the phone with Salesforce support, they suggested I should post here to find a solution to my problem. So now I am at the mercy of you kind developers prowling these boards and I am hopeful that together we can find a solution to my problem.

The Problem
Case ownership is transferring between users and my default support queue without the user's input, however, it appears as if the user is the one transferring the case. This can occur minutes after they initially take ownership, and sometimes it happens several hours later. It occurs with both open and closed cases, the latter be especially frustrating since the newly assigned owner will go to work the case without realizing it's already been closed. I have also verified that this is happening both during and after hours - when users are no longer logged into the system  - so I know that they are not the ones transferring the cases despite the Case feed suggesting otherwise. 

Investigation Thus Far I just want to thank everyone in advance for any support or guidance you can provide here. Please let me know if there is anything else I should provide that would help diagnose the issue here.

Thank you.

Ben