He was found to be 'of unsound mind' when he committed the murder.
The roof is structurally 'unsound'.
an 'unsound' [='unsafe'] building
(..) ice-cold sushi for breakfast. Rico. Well, since I'm doomed to die on this forsaken island, I, Melman Mankiewicz, being of sound mind and unsound body, have divided my estate equally among the three of you. Sorry, Alex. Hey! A latrine. Nice work, Melman. Outdoor plumbing. (..)2005 Madagascar