As circumstantial evidence goes, that's plenty.

Literal

Circumstantial-evidence [as-としちゃあ], sufficient [confirmation-だね].

状況証拠 'circumstantial evidence' — a legal term. としちゃあ is a casual contraction of としては 'as for, considering it as' — the は becomes ちゃ in relaxed speech. 十分 'sufficient, plenty.' だね is a casual male-speech confirmation. Has a detective/courtroom drama flavor.