J.J.,
There isn't really a great way to tell who deleted your issue. The only way to find it would be to restore a backup of your production environment containing that ticket into a test environment and extract it from there.
One recommendation would be to have the administrators remove that permission from the permission scheme so that people cannot delete issues.
If you can't restrict the permission, or are concerned that this is happening on a regular basis, you can also install an add-on to track who is deleting tickets (I am not affiliated with this add on in any way).
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