I think they’re saying it definitely was Mangione who was recorded at the hotel, which if he was checking in/out is pretty easy to prove. From there they lost track of him because they didn’t know his route or he just didn’t show up on any other cameras.
I agree that the wording is likely intentional to imply guilt, but is loose enough that they could claim that isn’t what they were doing.
Imagine it’ll be hard for them to Epstein him if all of the inmates care about his well-being