hi Venkatesh,
what is your database? (oracle, sql server?) perhaps there's someone out there with that db type that can verify the case syntax.
however, looking at it though it does look like the following logic (record selection style) should be occuring...
IF {?status} = 'COMPLETE/SUSPECT'
THEN r.status = 'COMPLETE'
ELSE r.status = {?status}
are you getting an error in query or are you not getting the results you need? and if so what is the full command object / query that you're using?
-jamie