Notes/Domino 6 and 7 Forum : Documents disappearing from database?

A strange problem was reported to me very recently involving a database which had suddenly and mysteriously lost some 648 documents. (I determined this by examining the document count in the database properties of that database and two other replicas.) The users reported that the documents had been present earlier in the day. (If the documents had disappeared from views due to Readers fields then they would still be included in the document count in the database.)
Suspecting finger trouble by a user and that the documents had been deleted I used a utility to check the deletion stubs, and found that although the database did contain a large number of deletion stubs, there were not over 600 for that day, so I became puzzled.
The only reasons that I am aware of that documents can disappear from a database replica other than by deletion (or cutting to the clipboard which is actually equivalent as it leaves deletion stubs behind) is through replication settings, ie:
- "remove documents not modified in the last X days" (where X is 90 by default)
- selective replication formulas, ie "Replicate a subset of documents" and "Select by formula" where a specific replica only includes documents which comply with a selective replication formula.
In either case documents which do not comply with the specified condition do not feature as deletion stubs, but simply are excluded from that particular replica.
I checked both of these conditions and neither of them applied in this case, ie no evidence of tampering by a local administrator.
Is it possible for a database replica to suddenly lose a large number of documents, apparently without them being deleted (or hidden by Readers fields)?