Probably not intended behavior.
When I visit derelict ships to complete "investigate death" gigs, the dead bodies are sometimes in the walls.
First gig: target on the floor, another body in the wall. Second gig: target body in the wall (as pictured).
Related (?): the bodies in the walls seem to glow slightly (i.e., are visible from range), which is a bummer for the "suspense" while searching.
[0.14.5.15] [observed 2025-10-13] [observed on all 2 / 2 investigate death ships I've seen, ~3 hours into this save]
(Edit: 2x bodies placed normally on investigate death mission #3)