In Recent History work center, few records are shown as Deleted.
Reproducing the Issue
Go to Recent History work center.
Navigate to Recent History view.
Select 'All' query.
Few of the records here are shown as <Deleted>.
If any of the user's last opened records are not found, then Recent History shows such records are deleted.
Recent History does not provide the details of who has deleted the records. It only logs the last 20 records which the user has accessed/opened.
To know what type of documents are deleted, change the query in any of the list and find out what type of documents are deleted.
Leads, Opportunities, Recent History , KBA , recent history , delete , LOD-CRM-EDG , C4C Edge , Problem