。
Needless to say, the search ended in failure.
Literal
Say-until-no [thing-ことだが] search [topic-は] futile-effort [in-に] ended.
言うまでもない ('goes without saying') is a set phrase, less classical-sounding than 言わずもがな but similar in meaning. 徒労 ('futile effort, vain labor') is a formal kango meaning wasted effort. ~に終わる ('end in X') is the pattern for outcomes. 捜索 ('search, investigation') is the formal term for official searches.