He was found to be 'of unsound mind' when he committed the murder.
The roof is structurally 'unsound'.
an 'unsound' [='unsafe'] building
(..) You know how I feel about that. Darn you! We can't blow cover again. - The building was coming down anyway. - What? You knocked down a building? It was on fire. Structurally unsound. It was coming down. Have you been listening to the police scanner again? I performed a public service. (..)2004 The Incredibles