Can't Restore Database Because of Rogue Log File
I'd bet the database didn't actually get dropped, and is still in use by SQL. 

Not sure why it isn't showing up in SSMS, but run the following query to see what database is still using it:

SELECT database_id, DB_NAME(database_id) AS DBName, name AS LogicalName, type_desc,
physical_name, convert(numeric(10,1),(size/128.0/1024.0)) SizeGB
FROM master.sys.master_files
ORDER BY database_id, type_desc desc, name


Is your Rogue database in the list? 

If you just do SELECT * FROM master.sys.databases, does it show Rogue? What does it show as the user_access_desc and state_desc?

What does the SQL errorlog say during the time in question? It should mention a database drop or change in status.